scmutil: introduce shortesthexnodeidprefix() We have scmutil.resolvehexnodeidprefix() for resolving a prefix to a full nodeid, so it makes sense to have the inverse method next to it. For now it just delegates to changelog.shortest(), but it will soon also make sure it's called on the unfiltered repo, to match resolvehexnodeidprefix(). Note that the change in show.py also makes it so the conversion from revnum to nodeid is done on the filtered repo, but that should be inconsequential since the revs are all from the filtered repo anyway. Differential Revision: https://phab.mercurial-scm.org/D3370

--- a/mercurial/scmutil.py	Fri Apr 13 11:00:30 2018 -0700
+++ b/mercurial/scmutil.py	Fri Apr 13 22:55:01 2018 -0700
@@ -443,6 +443,10 @@
     repo.changelog.rev(node)  # make sure node isn't filtered
     return node
 
+def shortesthexnodeidprefix(repo, hexnode, minlength=1):
+    """Find the shortest unambiguous prefix that matches hexnode."""
+    return repo.changelog.shortest(hexnode, minlength)
+
 def isrevsymbol(repo, symbol):
     """Checks if a symbol exists in the repo.