diff parser: prefer git headers over old unified diff headers

Makes the diff show both rename and chmod info and the diff.

rhodecode/lib/diffs.py

@@ -360,18 +360,6 b' class DiffProcessor(object):'
             stats = None
             msgs = []
 
-            if not head['a_file'] and head['b_file']:
-                op = 'A'
-                stats = ['b', NEW_FILENODE]
-                msgs.append('new file')
-            elif head['a_file'] and head['b_file']:
-                op = 'M'
-                stats = ['b', MOD_FILENODE]
-            elif head['a_file'] and not head['b_file']:
-                op = 'D'
-                stats = ['b', DEL_FILENODE]
-                msgs.append('deleted file')
-            else:
                 if head['deleted_file_mode']:
                     op = 'D'
                     stats = ['b', DEL_FILENODE]
@@ -392,6 +380,15 b' class DiffProcessor(object):'
                         stats = ['b', RENAMED_FILENODE] # might overwrite CHMOD_FILENODE
                         msgs.append('file renamed from %s to %s'
                                       % (head['rename_from'], head['rename_to']))
+                if op is None: # fall back: detect missed old style add or remove
+                    if not head['a_file'] and head['b_file']:
+                        op = 'A'
+                        stats = ['b', NEW_FILENODE]
+                        msgs.append('new file')
+                    elif head['a_file'] and not head['b_file']:
+                        op = 'D'
+                        stats = ['b', DEL_FILENODE]
+                        msgs.append('deleted file')
                     if op is None:
                         op = 'M'
                         stats = ['b', MOD_FILENODE]