Fix Dockerfile label placement and close connection on parse error

Move the OCI image source label from the build stage to the final
stage — in a multi-stage build only the final stage's labels end up
in the resulting image, so GHCR couldn't associate the package with
the repo.

Add _http.close() to on_parse_error for consistency with
on_response_complete — after a parse error the connection is in an
undefined state and should be torn down.

Author: SeanTAllen

Dockerfile

@@ -1,12 +1,12 @@
 FROM ghcr.io/ponylang/shared-docker-ci-standard-builder-with-libressl-4.2.0:release AS build
-LABEL org.opencontainers.image.source="https://github.com/ponylang/zulip-action"
 
 WORKDIR /src
 COPY . .
 
 RUN make build-action ssl=libressl static=true config=release
 
 FROM alpine:3.21
+LABEL org.opencontainers.image.source="https://github.com/ponylang/zulip-action"
 
 RUN apk add --no-cache ca-certificates
 

zulip_action/zulip_client.pony

@@ -121,6 +121,7 @@ actor ZulipClient is courier.HTTPClientConnectionActor
   fun ref on_parse_error(err: courier.ParseError) =>
     _notified = true
     _notify.failure("HTTP parse error")
+    _http.close()
 
   fun ref on_closed() =>
     """