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.