Nightly install: Only attempt OSX signing if not already signed (#19381)

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Author: anthony-c-martin

scripts/install_cli_nightly.sh

@@ -51,8 +51,10 @@ gh run download -R $repo $runId -n "bicep-release-$platform-$arch" --dir $tmpDir
 
 # Install
 if [[ $platform == "osx" ]]; then
-  # Ad-hoc sign the binary
-  codesign -s - "$tmpDir/bicep"
+  # Ad-hoc sign the binary if not already signed
+  if ! codesign -v "$tmpDir/bicep" 2>/dev/null; then
+    codesign -s - "$tmpDir/bicep"
+  fi
 fi
 
 mkdir -p $binaryPath
@@ -63,4 +65,4 @@ version=$("$binaryPath/bicep" --version | sed 's/^.* \([0-9]*\.[0-9]*\.[0-9]*\)
 echo "Installed Bicep $version from https://github.com/$repo/actions/runs/$runId to $binaryPath/bicep"
 
 # Cleanup
-rm -Rf $tmpDir
+rm -Rf $tmpDir