4660: file mode changes are interpreted as "empty diffs"

Misery

What version are you running?

3.0.3

What's the URL of the page containing the problem?

https://localhost/r/new/

What steps will reproduce the problem?

  1. Create a diff with "file mode" changes only
  2. Try to upload diff

What is the expected output? What do you see instead?

Expected: create a review request and show changed file modes.

See: The specified diff file is empty.

What operating system are you using? What browser?

Linux, Firefox

Please provide any additional information below.

$ hg diff -c 27 --git
diff --git a/dummy.png b/dummy.png
old mode 100755
new mode 100644
diff --git a/test.jpg b/test.jpg
old mode 100755
new mode 100644