gettext_po_exporter refactoring gone wrong

The recent small refactoring we did for translations has one big problem: it doesn't always work. I am surprised it works at all, but here's the traceback we get (https://pastebin.canonical.com/35859/):

2010-08-16 09:31:18 DEBUG Exporting objects for Данило Шеган, related to template scinotes in Scilab trunk
2010-08-16 09:32:23 DEBUG Removing lock file: /var/lock/launchpad-rosetta-export-queue.lock
Traceback (most recent call last):
  File "cronscripts/rosetta-export-queue.py", line 23, in <module>
    script.lock_and_run()
  File "/srv/staging.launchpad.net/staging/launchpad/lib/lp/services/scripts/base.py", line 285, in lock_and_run
    implicit_begin=implicit_begin, isolation=isolation)
  File "/srv/staging.launchpad.net/staging/launchpad/lib/lp/services/scripts/base.py", line 243, in run
    self.main()
  File "cronscripts/rosetta-export-queue.py", line 18, in main
    process_queue(self.txn, self.logger)
  File "/srv/staging.launchpad.net/staging/launchpad/lib/lp/translations/scripts/po_export_queue.py", line 385, in process_queue
    process_request(person, objects, format, logger)
  File "/srv/staging.launchpad.net/staging/launchpad/lib/lp/translations/scripts/po_export_queue.py", line 336, in process_request
    target_format=format)
  File "/srv/staging.launchpad.net/staging/launchpad/lib/lp/translations/utilities/translation_export.py", line 97, in exportTranslationFiles
    force_utf8=force_utf8)
  File "/srv/staging.launchpad.net/staging/launchpad/lib/lp/translations/utilities/gettext_po_exporter.py", line 377, in exportTranslationFile
    file_path, file_extension, encoded_file_content, mime_type)
UnboundLocalError: local variable 'encoded_file_content' referenced before assignment

The problem seems to be simple: encoded_file_content is referenced outside the for loop, and yet it's constructed inside the for loop. FWIW, the loop is over translation messages, so encoded_file_content should be outside the loop as well. It's a miracle this has passed our test suite.