Merge branch 'dup-frozen-argv-key' into 'master'

In order to use chomp! on the input later, we need to dup the ARGV input string for keys

Also updated the gitlab_key tests to freeze the ARGV variables.

Fixes https://gitlab.com/gitlab-org/gitlab-shell/issues/56

See merge request !84

lib/gitlab_keys.rb

@@ -22,7 +22,8 @@ class GitlabKeys
   def initialize
     @command = ARGV.shift
     @key_id = ARGV.shift
-    @key = ARGV.shift
+    key = ARGV.shift
+    @key = key.dup if key
     @auth_file = GitlabConfig.new.auth_file
   end

spec/gitlab_keys_spec.rb

@@ -284,7 +284,7 @@ describe GitlabKeys do
   def argv(*args)
     args.each_with_index do |arg, i|
-      ARGV[i] = arg
+      ARGV[i] = arg.freeze
     end
   end