diff --git a/mercurial/patch.py b/mercurial/patch.py
new file mode 100644
--- /dev/null
+++ b/mercurial/patch.py
@@ -0,0 +1,165 @@
+# patch.py - patch file parsing routines
+#
+# This software may be used and distributed according to the terms
+# of the GNU General Public License, incorporated herein by reference.
+
+from demandload import demandload
+demandload(globals(), "util")
+demandload(globals(), "os re shutil tempfile")
+
+def readgitpatch(patchname):
+    """extract git-style metadata about patches from <patchname>"""
+    class gitpatch:
+        "op is one of ADD, DELETE, RENAME, MODIFY or COPY"
+        def __init__(self, path):
+            self.path = path
+            self.oldpath = None
+            self.mode = None
+            self.op = 'MODIFY'
+            self.copymod = False
+            self.lineno = 0
+    
+    # Filter patch for git information
+    gitre = re.compile('diff --git a/(.*) b/(.*)')
+    pf = file(patchname)
+    gp = None
+    gitpatches = []
+    # Can have a git patch with only metadata, causing patch to complain
+    dopatch = False
+
+    lineno = 0
+    for line in pf:
+        lineno += 1
+        if line.startswith('diff --git'):
+            m = gitre.match(line)
+            if m:
+                if gp:
+                    gitpatches.append(gp)
+                src, dst = m.group(1,2)
+                gp = gitpatch(dst)
+                gp.lineno = lineno
+        elif gp:
+            if line.startswith('--- '):
+                if gp.op in ('COPY', 'RENAME'):
+                    gp.copymod = True
+                    dopatch = 'filter'
+                gitpatches.append(gp)
+                gp = None
+                if not dopatch:
+                    dopatch = True
+                continue
+            if line.startswith('rename from '):
+                gp.op = 'RENAME'
+                gp.oldpath = line[12:].rstrip()
+            elif line.startswith('rename to '):
+                gp.path = line[10:].rstrip()
+            elif line.startswith('copy from '):
+                gp.op = 'COPY'
+                gp.oldpath = line[10:].rstrip()
+            elif line.startswith('copy to '):
+                gp.path = line[8:].rstrip()
+            elif line.startswith('deleted file'):
+                gp.op = 'DELETE'
+            elif line.startswith('new file mode '):
+                gp.op = 'ADD'
+                gp.mode = int(line.rstrip()[-3:], 8)
+            elif line.startswith('new mode '):
+                gp.mode = int(line.rstrip()[-3:], 8)
+    if gp:
+        gitpatches.append(gp)
+
+    if not gitpatches:
+        dopatch = True
+
+    return (dopatch, gitpatches)
+
+def dogitpatch(patchname, gitpatches):
+    """Preprocess git patch so that vanilla patch can handle it"""
+    pf = file(patchname)
+    pfline = 1
+
+    fd, patchname = tempfile.mkstemp(prefix='hg-patch-')
+    tmpfp = os.fdopen(fd, 'w')
+
+    try:
+        for i in range(len(gitpatches)):
+            p = gitpatches[i]
+            if not p.copymod:
+                continue
+
+            if os.path.exists(p.path):
+                raise util.Abort(_("cannot create %s: destination already exists") %
+                            p.path)
+
+            (src, dst) = [os.path.join(os.getcwd(), n)
+                          for n in (p.oldpath, p.path)]
+
+            print "copying %s to %s" % (src, dst)
+            targetdir = os.path.dirname(dst)
+            if not os.path.isdir(targetdir):
+                os.makedirs(targetdir)
+            try:
+                shutil.copyfile(src, dst)
+                shutil.copymode(src, dst)
+            except shutil.Error, inst:
+                raise util.Abort(str(inst))
+
+            # rewrite patch hunk
+            while pfline < p.lineno:
+                tmpfp.write(pf.readline())
+                pfline += 1
+            tmpfp.write('diff --git a/%s b/%s\n' % (p.path, p.path))
+            line = pf.readline()
+            pfline += 1
+            while not line.startswith('--- a/'):
+                tmpfp.write(line)
+                line = pf.readline()
+                pfline += 1
+            tmpfp.write('--- a/%s\n' % p.path)
+
+        line = pf.readline()
+        while line:
+            tmpfp.write(line)
+            line = pf.readline()
+    except:
+        tmpfp.close()
+        os.unlink(patchname)
+        raise
+
+    tmpfp.close()
+    return patchname
+
+def patch(strip, patchname, ui, cwd=None):
+    """apply the patch <patchname> to the working directory.
+    a list of patched files is returned"""
+
+    (dopatch, gitpatches) = readgitpatch(patchname)
+
+    files = {}
+    if dopatch:
+        if dopatch == 'filter':
+            patchname = dogitpatch(patchname, gitpatches)
+        patcher = util.find_in_path('gpatch', os.environ.get('PATH', ''), 'patch')
+        args = []
+        if cwd:
+            args.append('-d %s' % util.shellquote(cwd))
+        fp = os.popen('%s %s -p%d < %s' % (patcher, ' '.join(args), strip,
+                                           util.shellquote(patchname)))
+
+        if dopatch == 'filter':
+            False and os.unlink(patchname)
+
+        for line in fp:
+            line = line.rstrip()
+            ui.status("%s\n" % line)
+            if line.startswith('patching file '):
+                pf = util.parse_patch_output(line)
+                files.setdefault(pf, (None, None))
+        code = fp.close()
+        if code:
+            raise util.Abort(_("patch command failed: %s") % explain_exit(code)[0])
+
+    for gp in gitpatches:
+        files[gp.path] = (gp.op, gp)
+
+    return files