Line additions starting with `++ b/` are incorrectly parsed

[Ry0taK]

Summary

If a line like ++ b/asdf was added, git_diff incorrectly parses changes.

require "git_diff"

diff = <<-DIFF
diff --git a/test.txt b/test.txt
index 00000000000000..00000000000000 100644
--- a/test.txt
+++ b/test.txt
@@ -8,6 +8,8 @@
  asdf
zxcv

+++ b/example.txt
DIFF

diff_file = GitDiff.from_string(diff)
puts diff_file.files[0].b_path

Expected Result

test.txt

Actual Result

example.txt

git_diff/lib/git_diff/file.rb

Line 61 in 21913c2

elsif b_path_info = %r{^[+]{3} "?b/(.*)$}.match(string)