--- a/mercurial/revset.py	Mon Feb 05 12:58:51 2018 +0530
+++ b/mercurial/revset.py	Mon Feb 05 12:59:57 2018 +0530
@@ -1841,7 +1841,7 @@
     keyflags = []
     for k in keys.split():
         fk = k
-        reverse = (k[0] == '-')
+        reverse = (k.startswith('-'))
         if reverse:
             k = k[1:]
         if k not in _sortkeyfuncs and k != 'topo':