diff -r ab6fd3205dad -r 0db6810e84e8 mercurial/patch.py
--- a/mercurial/patch.py	Sun Jan 18 15:15:40 2015 -0500
+++ b/mercurial/patch.py	Sat Jan 17 15:03:41 2015 -0800
@@ -1831,10 +1831,7 @@
                         header.append('new file mode %s\n' % mode)
                     elif ctx2.flags(f):
                         losedatafn(f)
-                # In theory, if tn was copied or renamed we should check
-                # if the source is binary too but the copy record already
-                # forces git mode.
-                if util.binary(tn):
+                if util.binary(to) or util.binary(tn):
                     if opts.git:
                         binarydiff = True
                     else: