Bump version to 27.0.0-rc.1 (#1912)

### What
Bump version to 27.0.0-rc.1, creating release branch.

### Why
Triggered by @mootz12 in
https://github.com/stellar/rs-soroban-sdk/actions/runs/27658089740.

### What is next

See the release instructions for a full rundown on the release process:
https://github.com/stellar/actions/blob/main/README-rust-release.md

Commit any changes to the `release/v27.0.0-rc.1` branch that are needed
in this release.

If this is a regular release releasing from `main`, merge this PR when
ready, and after merging, create a release for this version by going to
this link:
https://github.com/stellar/rs-soroban-sdk/releases/new?tag=v27.0.0-rc.1&title=27.0.0-rc.1

If this is a backport or patch release of a past version, see the
release instructions. When ready to release this branch create a release
by going to this link:

https://github.com/stellar/rs-soroban-sdk/releases/new?tag=v27.0.0-rc.1&title=27.0.0-rc.1&target=release/v27.0.0-rc.1

---------

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: Leigh <351529+leighmcculloch@users.noreply.github.com>

Author: github-actions[bot]

.github/workflows/test-with-openzeppelin-stellar-contracts.yml

@@ -67,6 +67,36 @@ jobs:
         is_a_contract=$(cargo metadata --no-deps --format-version 1 | jq -r --arg pwd "$(pwd)" '.packages[] | select(.manifest_path == "\($pwd)/Cargo.toml") | (any(.dependencies[]; .name == "soroban-sdk") and any(.targets[]; any(.crate_types[]; . == "cdylib")))')
         echo "is-a-contract=$is_a_contract" | tee -a $GITHUB_OUTPUT
 
+    - name: Align the local soroban-sdk version with the destination
+      working-directory: ${{ github.workspace }}
+      run: |
+        # The destination workspace pins soroban-sdk (and the other published
+        # rs-soroban-sdk crates) to a released version, and pulls crates such as
+        # soroban-poseidon from crates.io that depend on that same major. When the
+        # local checkout has bumped to a newer major (for example a 27.0.0-rc
+        # release), the [patch.crates-io] + `cargo update --precise` step below can't
+        # redirect those transitive soroban-sdk edges, because Cargo only applies a
+        # patch when the local version satisfies the requirement (soroban-poseidon's
+        # ^26). Relabel the local crates with the version the destination already
+        # resolves so the patch satisfies the requirement, collapsing every
+        # soroban-sdk edge onto the local checkout's code regardless of the bump.
+        dest_version=$(
+          cargo metadata --manifest-path stellar-contracts/Cargo.toml --format-version 1 \
+            | jq -r '.packages[] | select(.name == "soroban-sdk") | .version' \
+            | head -n1
+        )
+        local_version=$(
+          cargo metadata --manifest-path rs-soroban-sdk/Cargo.toml --format-version 1 --no-deps \
+            | jq -r '.packages[] | select(.name == "soroban-sdk") | .version'
+        )
+        echo "destination soroban-sdk version: ${dest_version:?could not determine destination soroban-sdk version}"
+        echo "local soroban-sdk version: $local_version"
+        if [ "$dest_version" != "$local_version" ]; then
+          escaped=$(printf '%s' "$local_version" | sed 's/[.]/\\./g')
+          sed -i "s|\"$escaped\"|\"$dest_version\"|g" rs-soroban-sdk/Cargo.toml
+          echo "Relabelled local rs-soroban-sdk crates from $local_version to $dest_version"
+        fi
+
     - name: Collect publishable rs-soroban-sdk crates
       working-directory: stellar-contracts
       run: |
@@ -118,8 +148,10 @@ jobs:
         #      checkout's version with `cargo update --precise`, so the transitive
         #      edges move onto it. Pinning (rather than letting cargo pick the highest
         #      compatible version) stops a newer *published* SDK from being chosen for a
-        #      transitive edge and re-splitting the graph. (Can't rescue an
-        #      incompatible-major transitive dep; that would need the remedy in #1723.)
+        #      transitive edge and re-splitting the graph. (When the local checkout is
+        #      an incompatible major, the "Align the local soroban-sdk version with the
+        #      destination" step above first relabels it to the destination's version,
+        #      so these requirements stay satisfiable; see #1723.)
         if [ -s "$RUNNER_TEMP/sdk-crates.tsv" ]; then
           # Don't emit a second [patch.crates-io] header if one already exists upstream.
           grep -q '^\[patch\.crates-io\]' Cargo.toml || printf '\n[patch.crates-io]\n' >> Cargo.toml

.github/workflows/test-with-soroban-examples.yml

@@ -42,16 +42,6 @@ jobs:
       matrix:
         working-directory: ${{ fromJSON(needs.collect-examples.outputs.dirs) }}
         experimental_spec_shaking_v2: [true, false]
-        # Exclude examples that depend on a crates.io package whose own soroban-sdk
-        # dependency is an incompatible major to the soroban-sdk under test. The
-        # [patch.crates-io] step below redirects transitive soroban-sdk copies to the
-        # local checkout, but Cargo only applies the patch when the local version
-        # satisfies the requirement. privacy-pools pulls soroban-poseidon 25.0.0
-        # (soroban-sdk ^25), which the local soroban-sdk (26.x) does not satisfy, so two
-        # soroban-sdk copies are compiled and linking fails with a duplicate lang item
-        # (panic_impl). https://github.com/stellar/rs-soroban-sdk/issues/1723
-        exclude:
-        - working-directory: privacy-pools
     defaults:
       run:
         working-directory: soroban-examples/${{ matrix.working-directory }}
@@ -82,6 +72,35 @@ jobs:
 
     - uses: stellar/actions/rust-cache@main
 
+    - name: Align the local soroban-sdk version with the example
+      working-directory: ${{ github.workspace }}
+      run: |
+        # The example pins soroban-sdk and may pull crates such as soroban-poseidon
+        # from crates.io that depend on a specific soroban-sdk major. When the local
+        # checkout has bumped to a newer major (for example a 27.0.0-rc release), the
+        # [patch.crates-io] + `cargo update --precise` step below can't redirect those
+        # transitive soroban-sdk edges, because Cargo only applies a patch when the
+        # local version satisfies the requirement (for example soroban-poseidon's ^25
+        # in privacy-pools). Relabel the local crates with the version the example
+        # already resolves so the patch satisfies the requirement, collapsing every
+        # soroban-sdk edge onto the local checkout's code regardless of the bump.
+        dest_version=$(
+          cargo metadata --manifest-path "soroban-examples/${{ matrix.working-directory }}/Cargo.toml" --format-version 1 \
+            | jq -r '.packages[] | select(.name == "soroban-sdk") | .version' \
+            | head -n1
+        )
+        local_version=$(
+          cargo metadata --manifest-path rs-soroban-sdk/Cargo.toml --format-version 1 --no-deps \
+            | jq -r '.packages[] | select(.name == "soroban-sdk") | .version'
+        )
+        echo "example soroban-sdk version: ${dest_version:?could not determine the example soroban-sdk version}"
+        echo "local soroban-sdk version: $local_version"
+        if [ "$dest_version" != "$local_version" ]; then
+          escaped=$(printf '%s' "$local_version" | sed 's/[.]/\\./g')
+          sed -i "s|\"$escaped\"|\"$dest_version\"|g" rs-soroban-sdk/Cargo.toml
+          echo "Relabelled local rs-soroban-sdk crates from $local_version to $dest_version"
+        fi
+
     - name: Collect publishable rs-soroban-sdk crates
       run: |
         # Collect the publishable rs-soroban-sdk crates, their directories, and their
@@ -143,9 +162,10 @@ jobs:
         #      checkout's version with `cargo update --precise`, so the transitive
         #      edges move onto it. Pinning (rather than letting cargo pick the highest
         #      compatible version) stops a newer *published* SDK from being chosen for a
-        #      transitive edge and re-splitting the graph. (Can't rescue an
-        #      incompatible-major transitive dep, so the matrix exclusion is still
-        #      needed.)
+        #      transitive edge and re-splitting the graph. (When the local checkout is
+        #      an incompatible major, the "Align the local soroban-sdk version with the
+        #      example" step above first relabels it to the example's version, so these
+        #      requirements stay satisfiable; see #1723.)
         workspace_root=$(cargo metadata --format-version 1 --no-deps | jq -r '.workspace_root')
         if [ -s "$RUNNER_TEMP/sdk-crates.tsv" ]; then
           # Don't emit a second [patch.crates-io] header if one already exists upstream.