Index: Lib/difflib.py
===================================================================
--- Lib/difflib.py	(revision 77065)
+++ Lib/difflib.py	(working copy)
@@ -1161,18 +1161,18 @@
 
     The unidiff format normally has a header for filenames and modification
     times.  Any or all of these may be specified using strings for
-    'fromfile', 'tofile', 'fromfiledate', and 'tofiledate'.  The modification
-    times are normally expressed in the format returned by time.ctime().
+    'fromfile', 'tofile', 'fromfiledate', and 'tofiledate'. The modification
+    times are normally expressed in ISO 8601 compatible timestamps.
 
     Example:
 
     >>> for line in unified_diff('one two three four'.split(),
     ...             'zero one tree four'.split(), 'Original', 'Current',
-    ...             'Sat Jan 26 23:30:50 1991', 'Fri Jun 06 10:20:52 2003',
+    ...             '1991-01-26 23:30:50', '2003-06-06 10:20:52',
     ...             lineterm=''):
     ...     print line
-    --- Original Sat Jan 26 23:30:50 1991
-    +++ Current Fri Jun 06 10:20:52 2003
+    --- Original        1991-01-26 23:30:50
+    +++ Current Fri 2003-06-06 10:20:52
     @@ -1,4 +1,4 @@
     +zero
      one
@@ -1185,8 +1185,12 @@
     started = False
     for group in SequenceMatcher(None,a,b).get_grouped_opcodes(n):
         if not started:
-            yield '--- %s %s%s' % (fromfile, fromfiledate, lineterm)
-            yield '+++ %s %s%s' % (tofile, tofiledate, lineterm)
+            if fromfiledate:
+                fromfiledate = '\t%s' % fromfiledate
+            if tofiledate:
+                tofiledate = '\t%s' % tofiledate
+            yield '--- %s%s%s' % (fromfile, fromfiledate, lineterm)
+            yield '+++ %s%s%s' % (tofile, tofiledate, lineterm)
             started = True
         i1, i2, j1, j2 = group[0][1], group[-1][2], group[0][3], group[-1][4]
         yield "@@ -%d,%d +%d,%d @@%s" % (i1+1, i2-i1, j1+1, j2-j1, lineterm)
@@ -1232,8 +1236,8 @@
     >>> print ''.join(context_diff('one\ntwo\nthree\nfour\n'.splitlines(1),
     ...       'zero\none\ntree\nfour\n'.splitlines(1), 'Original', 'Current',
     ...       'Sat Jan 26 23:30:50 1991', 'Fri Jun 06 10:22:46 2003')),
-    *** Original Sat Jan 26 23:30:50 1991
-    --- Current Fri Jun 06 10:22:46 2003
+    *** Original	Sat Jan 26 23:30:50 1991
+    --- Current	Fri Jun 06 10:22:46 2003
     ***************
     *** 1,4 ****
       one
@@ -1251,8 +1255,12 @@
     prefixmap = {'insert':'+ ', 'delete':'- ', 'replace':'! ', 'equal':'  '}
     for group in SequenceMatcher(None,a,b).get_grouped_opcodes(n):
         if not started:
-            yield '*** %s %s%s' % (fromfile, fromfiledate, lineterm)
-            yield '--- %s %s%s' % (tofile, tofiledate, lineterm)
+            if fromfiledate:
+                fromfiledate = '\t%s' % fromfiledate
+            if tofiledate:
+                tofiledate = '\t%s' % tofiledate
+            yield '*** %s%s%s' % (fromfile, fromfiledate, lineterm)
+            yield '--- %s%s%s' % (tofile, tofiledate, lineterm)
             started = True
 
         yield '***************%s' % (lineterm,)