diff parser: match the header order of hg diff --git patches

The output might look like:

  diff --git a/A b/B
  old mode 100644
  new mode 100755
  rename from A
  rename to B
  --- a/A
  +++ b/B

Such files were shown as 'modified binary file chmod 100644 => 100755' without
diff.

Now the chmod and diff will be shown ... but still not the rename.

Correct parsing of headers do require a better parser - one do not just use a
regexp.

rhodecode/lib/diffs.py

@@ -172,11 +172,11 b' class DiffProcessor(object):'
     _hg_header_re = re.compile(r"""
         #^diff[ ]--git
             [ ]a/(?P<a_path>.+?)[ ]b/(?P<b_path>.+?)\n
+        (?:^old[ ]mode[ ](?P<old_mode>\d+)\n
+           ^new[ ]mode[ ](?P<new_mode>\d+)(?:\n|$))?
         (?:^similarity[ ]index[ ](?P<similarity_index>\d+)%(?:\n|$))?
         (?:^rename[ ]from[ ](?P<rename_from>\S+)\n
            ^rename[ ]to[ ](?P<rename_to>\S+)(?:\n|$))?
-        (?:^old[ ]mode[ ](?P<old_mode>\d+)\n
-           ^new[ ]mode[ ](?P<new_mode>\d+)(?:\n|$))?
         (?:^new[ ]file[ ]mode[ ](?P<new_file_mode>.+)(?:\n|$))?
         (?:^deleted[ ]file[ ]mode[ ](?P<deleted_file_mode>.+)(?:\n|$))?
         (?:^index[ ](?P<a_blob_id>[0-9A-Fa-f]+)