Unset GL_ID and GL_PROTOCOL immediately

Neither other code executing in the hook process nor subprocesses of
the hook process need access to the GL_ID / GL_PROTOCOL variables so
we can just unset them the moment we fetch them.

hooks/post-receive

@@ -4,12 +4,9 @@
 # will be processed properly.
 
 refs = $stdin.read
-key_id  = ENV['GL_ID']
+key_id  = ENV.delete('GL_ID')
 repo_path = Dir.pwd
 
-# reset GL_ID env since we already got its value
-ENV['GL_ID'] = nil
-
 require_relative '../lib/gitlab_custom_hook'
 require_relative '../lib/gitlab_post_receive'
 

hooks/pre-receive

@@ -4,8 +4,8 @@
 # will be processed properly.
 
 refs = $stdin.read
-key_id  = ENV['GL_ID']
-protocol = ENV['GL_PROTOCOL']
+key_id  = ENV.delete('GL_ID')
+protocol = ENV.delete('GL_PROTOCOL')
 repo_path = Dir.pwd
 
 require_relative '../lib/gitlab_custom_hook'
@@ -15,8 +15,5 @@ if GitlabAccess.new(repo_path, key_id, refs, protocol).exec &&
     GitlabCustomHook.new.pre_receive(refs, repo_path)
   exit 0
 else
-  # reset GL_ID env since we stop git push here
-  ENV['GL_ID'] = nil
-  
   exit 1
 end