Error 500 when editing a file while user name contains <...>

Summary

Editing a file (precisely committing it) does not work if the user's display name contains <...>.

Steps to reproduce

• change display name to <something>
• edit file
• commit

What is the current bug behavior?

Error 500

What is the expected correct behavior?

Commit is created.

Relevant logs

Rugged::InvalidError
failed to parse signature - Neither `name` nor `email` should contain angle brackets chars.

in create_commit.

Possible fixes

• disallow changing a user name to <...>
• quote/escape user name when committing