mercurial/cmdutil.py

--- a/mercurial/cmdutil.py	Thu Oct 07 18:05:04 2010 -0500
+++ b/mercurial/cmdutil.py	Thu Oct 07 18:24:29 2010 -0500
@@ -111,6 +111,15 @@
         limit = None
     return limit
 
+def revsingle(repo, revspec, default=None):
+    if not revspec:
+        return repo[default]
+
+    l = revrange(repo, [revspec])
+    if len(l) < 1:
+        raise util.Abort("empty revision set")
+    return repo[l[-1]]
+
 def revpair(repo, revs):
     if not revs:
         return repo.dirstate.parents()[0], None