title: Git: Getting commits with a ticket number
body: <p>Okay, so I'm trying to find out if a ticket has been included in my release branch. The tickets are all built out of a project id and an id number, e.g. (PRO-123). I've tried this command:</p>
  
  <pre><code>git log --date=short --format="%h: %ad (%cn)  %s" --abbrev-commit --grep='[A-Z]+-[0-9]+'
  </code></pre>
  
  <p>But it's not returning anything. If I take away the <code>--grep</code> part there's loads of matches to the pattern. For instance:</p>
  
  <pre>
  a6fdcd0: 2016-03-16 (ajfaraday)  Merge remote-tracking branch 'origin/develop_5.2_customer' into release_5.2_customer
  85d107a: 2016-03-16 (username)  Merge pull request #477 from myapp/fix_CST-827_outline_method_in_use_check
  6024bda: 2016-03-16 (Andrew Faraday)  Merge pull request #473 from myapp/fix_CST-810_soap_container_create_bounds
  eec2a61: 2016-03-16 (ajfaraday)  added missing stubs
  c03b3cb: 2016-03-15 (username)  Merge pull request #472 from myapp/fix_CST-490_options_are_clickable_for_user_without_module_admin_rights
  728539b: 2016-03-15 (username)  Merge pull request #474 from myapp/fix_CST-873_hidden_error_on_pev_validation
  4a11dd7: 2016-03-15 (username)  Merge pull request #475 from myapp/fix_CST-854_copy_process_version_project_element_values
  4a5af44: 2016-03-15 (ajfaraday)  CST-854: fixed in-use check for methods
  </pre>
  
  <p>What am I doing wrong?</p>