…ound

In case we have a more specific tag pattern to search on a branch,
 and this pattern does not match any tag in the branch, it's preferable
 to have a limit to the describe search for performance reasons.

As the implementation was a counter, when visiting many parents without resetting the counter,
the returned distance was not correct.

Using the DepthWalk.RevWalk has two benefits:
 - it can limit the depths
 - it allows accessing the depth of the current commit instead of trying to do it with custom code

 - Tags at same depth: no logic implemented to specify which one is selected, so I put one
  more commit in the test to have different depths.
 - Version from label=0 plus distance=0 (single commit, no tag), not sure why the test was expecting "1" as a version.