dune subst output depends on git version

[nojb]

Not sure this is something that should be fixed by dune, but am opening the issue just to put it out: dune subst calls git describe, but the number of digits used in the "short hash" depends on the version of git as far as I can see. Recently I was bitten by this where the same commit built under Unix (Ubuntu 18.04) and Windows (Cygwin) ended up with different strings substituted.

git describe accepts a --abbrev=<n> argument to specify how many digits to use in the short hash, but it is not clear that using this is the right thing to do.

[jberdine]

Is this covered by #4857 or does subst use a different path than build-info?

[nojb]

Is this covered by #4857 or does subst use a different path than build-info?

From a quick glance it looks like it is. Thanks for the pointer!