Add repro for gh10234

[gridbugs]

Adds repro test for #10234

[rgrinberg]

This should be same as #9700 as well - but on the lock file generation side. We're currently generating file://, but it's buggy. So we need to make it robust like copy.

[gridbugs]

I don't understand how this can be fixed by removing the copy constructor. The issue here is that out of date build commands are being run from the lockfile. We would need a way of checking if the opam file in the pinned package had changed and regenerating its lockfile if necessary, or a way of running the build commands from the pinned package's opam file directly rather than from its lockfile.

[rgrinberg]

Good point. Why are we even recording the build command for pins again? If we have the checksum for the source, that already fixes the build command. If we don't have the cehcksum, the build command is useless anyway