diff -r e2ed92f4c0f7 -r 226df1808f16 mercurial/mdiff.py
--- a/mercurial/mdiff.py	Sat Feb 17 04:50:06 2007 -0200
+++ b/mercurial/mdiff.py	Tue Feb 20 20:55:23 2007 +0100
@@ -5,7 +5,7 @@
 # This software may be used and distributed according to the terms
 # of the GNU General Public License, incorporated herein by reference.
 
-import bdiff, mpatch, re, struct, util
+import bdiff, mpatch, re, struct, util, md5
 
 def splitnewlines(text):
     '''like str.splitlines, but only split on newlines.'''
@@ -57,6 +57,11 @@
     epoch = util.datestr((0, 0))
 
     if not opts.text and (util.binary(a) or util.binary(b)):
+        def h(v):
+            # md5 is used instead of sha1 because md5 is supposedly faster
+            return md5.new(v).digest()
+        if a and b and len(a) == len(b) and h(a) == h(b):
+            return ""
         l = ['Binary file %s has changed\n' % fn]
     elif not a:
         b = splitnewlines(b)