git-p4: Add copy detection support

Add new config options:
    git-p4.detectCopies         - Enable copy detection.
    git-p4.detectCopiesHarder   - Find copies harder.
The detectCopies option should be set to a true/false value.
The detectCopiesHarder option should be set to true/false value.
P4Submit can now process diff-tree C status and integrate files accordingly.

Signed-off-by: Vitor Antunes <vitor.hda@gmail.com>
Acked-by: Pete Wyckoff <pw@padd.com>
Acked-by: Tor Arvid Lund <torarvid@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

contrib/fast-import/git-p4

@@ -623,6 +623,12 @@ class P4Submit(Command):
         else:
             diffOpts = ""
 
+        if gitConfig("git-p4.detectCopies").lower() == "true":
+            diffOpts += " -C"
+
+        if gitConfig("git-p4.detectCopiesHarder").lower() == "true":
+            diffOpts += " --find-copies-harder"
+
         diff = read_pipe_lines("git diff-tree -r %s \"%s^\" \"%s\"" % (diffOpts, id, id))
         filesToAdd = set()
         filesToDelete = set()
@@ -646,6 +652,16 @@ class P4Submit(Command):
                 filesToDelete.add(path)
                 if path in filesToAdd:
                     filesToAdd.remove(path)
+            elif modifier == "C":
+                src, dest = diff['src'], diff['dst']
+                p4_system("integrate -Dt \"%s\" \"%s\"" % (src, dest))
+                if diff['src_sha1'] != diff['dst_sha1']:
+                    p4_system("edit \"%s\"" % (dest))
+                if isModeExecChanged(diff['src_mode'], diff['dst_mode']):
+                    p4_system("edit \"%s\"" % (dest))
+                    filesToChangeExecBit[dest] = diff['dst_mode']
+                os.unlink(dest)
+                editedFiles.add(dest)
             elif modifier == "R":
                 src, dest = diff['src'], diff['dst']
                 p4_system("integrate -Dt \"%s\" \"%s\"" % (src, dest))