style: don't use capital letter for constant

style: don't use capital letter for constant

For better or worse, our coding do not use all caps for constants. We rename
constant name introduced in a5009789960c.

--- a/mercurial/transaction.py	Sat Jun 04 11:16:08 2016 -0700
+++ b/mercurial/transaction.py	Sat Apr 16 15:59:30 2016 -0700
@@ -32,9 +32,9 @@
 ])
 
 class GenerationGroup(object):
-    ALL='all'
-    PREFINALIZE='prefinalize'
-    POSTFINALIZE='postfinalize'
+    all='all'
+    prefinalize='prefinalize'
+    postfinalize='postfinalize'
 
 def active(func):
     def _active(self, *args, **kwds):
@@ -289,7 +289,7 @@
         # but for bookmarks that are handled outside this mechanism.
         self._filegenerators[genid] = (order, filenames, genfunc, location)
 
-    def _generatefiles(self, suffix='', group=GenerationGroup.ALL):
+    def _generatefiles(self, suffix='', group=GenerationGroup.all):
         # write files registered for generation
         any = False
         for id, entry in sorted(self._filegenerators.iteritems()):
@@ -297,8 +297,8 @@
             order, filenames, genfunc, location = entry
 
             # for generation at closing, check if it's before or after finalize
-            postfinalize = group == GenerationGroup.POSTFINALIZE
-            if (group != GenerationGroup.ALL and
+            postfinalize = group == GenerationGroup.postfinalize
+            if (group != GenerationGroup.all and
                 (id in postfinalizegenerators) != (postfinalize)):
                 continue
 
@@ -427,13 +427,13 @@
         '''commit the transaction'''
         if self.count == 1:
             self.validator(self)  # will raise exception if needed
-            self._generatefiles(group=GenerationGroup.PREFINALIZE)
+            self._generatefiles(group=GenerationGroup.prefinalize)
             categories = sorted(self._finalizecallback)
             for cat in categories:
                 self._finalizecallback[cat](self)
             # Prevent double usage and help clear cycles.
             self._finalizecallback = None
-            self._generatefiles(group=GenerationGroup.POSTFINALIZE)
+            self._generatefiles(group=GenerationGroup.postfinalize)
 
         self.count -= 1
         if self.count != 0: