@@ -, +, @@ 
------------------------------------------------------------------------
--- trac/util/datefmt.py	(revision 11892)
+++ trac/util/datefmt.py	(revision 11893)
@@ -538,8 +538,9 @@ 
     if formats[0].find('%(a)s') != -1:
         names = get_period_names(locale=locale)
         for period, name in names.iteritems():
-            name = name.lower()
-            period_names[name] = period
+            if period in ('am', 'pm'):
+                name = name.lower()
+                period_names[name] = period
     regexp.extend(period_names.iterkeys())
 
     return {
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