destutil: add new local variable to increase readability

Before this patch, local variable 'heads' is used not only for "all
branch heads" but also for "branch heads other than current parent".

This patch newly adds local variable 'otherheads' for the latter
purpose, to increase readability.

mercurial/destutil.py

@@ -360,10 +360,10 b' def _statusotherbranchheads(ui, repo):'
     l = len(heads)
     if repo.revs('%ln and parents()', heads):
         # we are on a head
-        heads = repo.revs('%ln - parents()', heads)
-        if heads and l != len(heads):
+        otherheads = repo.revs('%ln - parents()', heads)
+        if otherheads and l != len(otherheads):
             ui.status(_('%i other heads for branch "%s"\n') %
-                      (len(heads), currentbranch))
+                      (len(otherheads), currentbranch))
 
 def statusotherdests(ui, repo):
     """Print message about other head"""