logcmdutil: add a type annotation

This wasn't actually required in the end, as there was a real bug
found by pytype, but the annotation helped me figure that out. We can
drop this patch if that's the preference.

Differential Revision: https://phab.mercurial-scm.org/D7382

mercurial/logcmdutil.py

@@ -42,6 +42,16 b' from .utils import ('
 )
 
 
+if not globals():
+    from typing import (
+        Any,
+        Tuple,
+    )
+
+    for t in (Any, Tuple):
+        assert t
+
+
 def getlimit(opts):
     """get the log limit according to option -l/--limit"""
     limit = opts.get(b'limit')
@@ -843,6 +853,7 b' def _initialrevs(repo, opts):'
 
 
 def getrevs(repo, pats, opts):
+    # type: (Any, Any, Any) -> Tuple[smartset.BaseSet, changesetdiffer]
     """Return (revs, differ) where revs is a smartset
 
     differ is a changesetdiffer with pre-configured file matcher.