Do not error out on pot files with no messages

language is None for them, so skip all the extra processing that really
applies only to po files.
1 job for master in 1 minute and 20 seconds (queued for 1 second)
Status Job ID Name Coverage
failed #291442


Name Stage Failure
test Test
  Building wheel for diff-match-patch ( started
Building wheel for diff-match-patch ( finished with status 'done'
Stored in directory: /root/.cache/pip/wheels/f2/72/a3/8c2adafbe9afc22a1e65cfc412982e0061199c0092b1be11d9
Successfully built mysqlclient pyicu translate-toolkit diff-match-patch
Installing collected packages: sqlparse, pytz, django, pillow, mysqlclient, six, chardet, certifi, idna, urllib3, requests, oauthlib, requests-oauthlib, PyJWT, defusedxml, python3-openid, social-auth-core, social-auth-app-django, django-debug-toolbar, markdown, pyicu, diff-match-patch, translate-toolkit
Successfully installed PyJWT-1.7.1 certifi-2019.3.9 chardet-3.0.4 defusedxml-0.6.0 diff-match-patch-20121119 django-2.2.1 django-debug-toolbar-1.11 idna-2.8 markdown-3.0.1 mysqlclient-1.4.2.post1 oauthlib-3.0.1 pillow-6.0.0 pyicu-2.3.1 python3-openid-3.1.0 pytz-2019.1 requests-2.21.0 requests-oauthlib-1.2.0 six-1.12.0 social-auth-app-django-3.1.0 social-auth-core-3.1.0 sqlparse-0.3.0 translate-toolkit-2.3.1 urllib3-1.24.3
$ python compile-trans --settings=damnedlies.settings_tests
CommandError: Can't find msgfmt. Make sure you have GNU gettext tools 0.15 or newer installed.
ERROR: Job failed: exit code 1