Add support for prefixed version tags in scc

[sbesson]

With this commit, we sould now be able to tag the repository using
semver's recommended vX.Y.Z-METADATA. get_git_version has been updated to
recognize this new format so that both scc version and python setup.py sdist should work fine.

To test this PR:

• check the unit tests pass
• create a local annotated tag e.g. v0.5.0-rc1 and check python scc/main.py version and python setup.py sdist use the correct version

/cc @rleigh

[joshmoore]

👍 Looks good from my side. @rleigh-dundee?

[ghost]

Why not call git describe with --match 'v.*' so that it can only ever match valid tags? Then you don't need any additional checking or mangling of the version?

[sbesson]

@rleigh: the idea was to follow semver.org as much as possible and to valid the entire tag version like we do for our other repos at the moment.

[ghost]

@sbesson what I mean is, git describe will find the first tag, and this might be anything, not necessarily a version tag, and this will break things. So adding --match will make it search the history until it finds a real release version tag. The validation you're doing on top of this is fine, but there's little point in picking up non-version tags by accident. This just adds robustness to avoid future problems.

[sbesson]

Gotcha. Yes will push another commit. Thanks.

[sbesson]

Note that this would imply redoing the tags and creating vVERSION tags on this repo first. Any veto?

[ghost]

You only need one tag creating, just the latest one so that stuff will work until we tag the next release. Unless it's safe to do it for the whole history; but that doesn't need doing right now I think.

[bpindelski]

All looks good here. Unit tests pass and annotated tags get picket up as expected. Looks good to merge.

[joshmoore]

🚢 ?

[sbesson]

Merging for 0.5.0.