Subject of the issue

Unicode characters in filenames breaks diffing

Your environment

• git version 2.20.1
• git (1.5.0)
• ruby 2.6.4p104 (2019-08-28 revision 67798) [x86_64-linux]

Steps to reproduce

$ mkdir -p /tmp/test&&cd /tmp/test$ git init$printf'\xE2\x98\xA0'# print a skull and crossbones symbol$ touch'some_file'$ git add.$ git commit -m"init"$ touch'my_other_file_\xE2\x98\xA0'$ git add.$ git commit -m"commit"

git=Git.init'/tmp/test'git.diff('@^').each{ |x| ...}

Expected behaviour

The diff to be produced as usual

Actual behaviour

NoMethodError: undefined method `[]' for nil:NilClass

The first line of a diff is usually something likegit --diff a/somefile b/somefile, but when the filename contains a unicode character, the filenames are escaped, (e.g.diff --git "a/my_other_file_\\xE2\\x98\\xA0" "b/my_other_file_\\xE2\\x98\\xA0") andthis regex fails to detect the line.