Remove timestamps from `locale/gitlab.pot`

This will help us avoid conflicts when regenerating the pot file, the
timestamps aren't used by Crowdin.

lib/tasks/gettext.rake

@@ -20,16 +20,22 @@ namespace :gettext do
   end
 
   task :regenerate do
+    pot_file = 'locale/gitlab.pot'
     # Remove all translated files, this speeds up finding
     FileUtils.rm Dir['locale/**/gitlab.*']
     # remove the `pot` file to ensure it's completely regenerated
-    FileUtils.rm_f 'locale/gitlab.pot'
+    FileUtils.rm_f pot_file
 
     Rake::Task['gettext:find'].invoke
 
     # leave only the required changes.
     `git checkout -- locale/*/gitlab.po`
 
+    # Remove timestamps from the pot file
+    pot_content = File.read pot_file
+    pot_content.gsub!(/^"POT?\-(?:Creation|Revision)\-Date\:.*\n/, '')
+    File.write pot_file, pot_content
+
     puts <<~MSG
     All done. Please commit the changes to `locale/gitlab.pot`.
 

locale/gitlab.pot

@@ -8,8 +8,6 @@ msgid ""
 msgstr ""
 "Project-Id-Version: gitlab 1.0.0\n"
 "Report-Msgid-Bugs-To: \n"
-"POT-Creation-Date: 2018-07-10 17:09+0300\n"
-"PO-Revision-Date: 2018-07-10 17:09+0300\n"
 "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
 "Language-Team: LANGUAGE <LL@li.org>\n"
 "Language: \n"