revset: use a single return statement in matcher function

This makes it easy to insert post processing and debug code on the returned
value.

mercurial/revset.py

@@ -2063,8 +2063,10 b' def match(ui, spec, repo=None):'
     weight, tree = optimize(tree, True)
     def mfunc(repo, subset):
         if util.safehasattr(subset, 'set'):
-            return getset(repo, subset, tree)
-        return getset(repo, baseset(subset), tree)
+            result = getset(repo, subset, tree)
+        else:
+            result = getset(repo, baseset(subset), tree)
+        return result
     return mfunc
 
 def formatspec(expr, *args):