phase: avoid a no-op resolution of revset from revnums

I was surprised that `scmutil.revrange()` supports integers in the
list of revsets. I think it's clearer to not pass a list that's known
to contain only integers into the function.

Differential Revision: https://phab.mercurial-scm.org/D11559

mercurial/commands.py

@@ -5219,13 +5219,13 b' def phase(ui, repo, *revs, **opts):'
     # look for specified revision
     revs = list(revs)
     revs.extend(opts[b'rev'])
-    if not revs:
+    if revs:
+        revs = scmutil.revrange(repo, revs)
+    else:
         # display both parents as the second parent phase can influence
         # the phase of a merge commit
         revs = [c.rev() for c in repo[None].parents()]
 
-    revs = scmutil.revrange(repo, revs)
-
     ret = 0
     if targetphase is None:
         # display