Fix cross repo Go references when not pointing at a tagged version

[mmanela]

Fixes GRAPH-129

This PR resolves a mismatch with how scip-go would generate the version string when not pointing at a tagged module version string. This mismatch would break cross-repo references.

Background

When indexing a repo who's head commit was not tagged, scip-go sets the version as the first 12 characters of the HEAD commit sha. However, when referencing a module at that same non-tagged commit, scip-go would just set the version to the pseudo-version string.

To fix this, we will consistently use the sha1 when pointing at a non-tagged commit. If you point at a tagged commit (e.g. v1.2.3) then we do not change anything and still just use the proper version string.

Result

Below are the generated version strings when pointing at the latest commit on github.com/sourcegraph/conc

Definition

definition scip-go gomod github.com/sourcegraph/conc 5f936abd7ae8 `github.com/sourcegraph/conc/pool`/NewWithResults().

Reference

reference scip-go gomod github.com/sourcegraph/conc 5f936abd7ae8 `github.com/sourcegraph/conc/pool`/NewWithResults().

[varungandhi-src]

Oh, sorry I forgot to submit the review yesterday. 🤦🏽

[varungandhi-src]

I think this looks OK, but I think we should be explicitly stripping out the build metadata suffix, if present. That's technically a different bug, but a bug nonetheless, and it's very much related to the code you're modifying.