Fix 500 error when group name ends with git

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

changelogs/unreleased/dz-fix-500-group-git.yml

+---
+title: Fix 500 error when group name ends with git
+merge_request: 7630
+author: 

lib/gitlab/regex.rb

@@ -9,7 +9,7 @@ module Gitlab
     # `NAMESPACE_REGEX_STR`, with the negative lookbehind assertion removed. This means that the client-side validation
     # will pass for usernames ending in `.atom` and `.git`, but will be caught by the server-side validation.
     NAMESPACE_REGEX_STR_SIMPLE = '[a-zA-Z0-9_\.][a-zA-Z0-9_\-\.]*[a-zA-Z0-9_\-]|[a-zA-Z0-9_]'.freeze
-    NAMESPACE_REGEX_STR = "(?:#{NAMESPACE_REGEX_STR_SIMPLE})(?<!\.git|\.atom)".freeze
+    NAMESPACE_REGEX_STR = '(?:' + NAMESPACE_REGEX_STR_SIMPLE + ')(?<!\.git|\.atom)'.freeze
 
     def namespace_regex
       @namespace_regex ||= /\A#{NAMESPACE_REGEX_STR}\z/.freeze

spec/routing/routing_spec.rb

@@ -261,7 +261,7 @@ describe "Authentication", "routing" do
 end
 
 describe "Groups", "routing" do
-  let(:name) { 'complex.group-name' }
+  let(:name) { 'complex.group-namegit' }
 
   it "to #show" do
     expect(get("/groups/#{name}")).to route_to('groups#show', id: name)