diff --git a/mercurial/dirstate.py b/mercurial/dirstate.py
--- a/mercurial/dirstate.py
+++ b/mercurial/dirstate.py
@@ -230,7 +230,8 @@ class dirstate(object):
             self._pl = p
 
     def invalidate(self):
-        for a in "_map _copymap _foldmap _branch _pl _dirs _ignore".split():
+        for a in ("_map", "_copymap", "_foldmap", "_branch", "_pl", "_dirs",
+                "_ignore"):
             if a in self.__dict__:
                 delattr(self, a)
         self._dirty = False
diff --git a/mercurial/localrepo.py b/mercurial/localrepo.py
--- a/mercurial/localrepo.py
+++ b/mercurial/localrepo.py
@@ -733,7 +733,7 @@ class localrepository(repo.repository):
         self._branchcachetip = None
 
     def invalidate(self):
-        for a in "changelog manifest".split():
+        for a in ("changelog", "manifest"):
             if a in self.__dict__:
                 delattr(self, a)
         self.invalidatecaches()
diff --git a/mercurial/util.py b/mercurial/util.py
--- a/mercurial/util.py
+++ b/mercurial/util.py
@@ -1099,7 +1099,7 @@ def parsedate(date, formats=None, defaul
         if not defaults:
             defaults = {}
         now = makedate()
-        for part in "d mb yY HI M S".split():
+        for part in ("d", "mb", "yY", "HI", "M", "S"):
             if part not in defaults:
                 if part[0] in "HMS":
                     defaults[part] = "00"
@@ -1146,7 +1146,7 @@ def matchdate(date):
 
     def upper(date):
         d = dict(mb="12", HI="23", M="59", S="59")
-        for days in "31 30 29".split():
+        for days in ("31", "30", "29"):
             try:
                 d["d"] = days
                 return parsedate(date, extendeddateformats, d)[0]