Code review comment for lp:~henninge/launchpad/bug-506925-oops-export

= Bug 506925 =

Each PO file has a standard header with information about the file. One of the fields in that header is "Last-Translator" which contains the name and email address of the last person that did a translation in this file. Upon export from Launchpad, this field is filled with the display_name (or title? who cares) of the last translators IPerson object (and email address). This may contain non-ascii characters as in https://launchpad.net/~danilo. The header also has a "Content-Type" field that declares the character encoding of the file. This bug used to surface when that field did not contain a charset that could represent the translators name (ideally utf-8).

This problem is not new as such clashes have happened with translations, too, which also may contain non-ascii characters. The export routine alredy knows how to deal with this and simply changes the encoding of the file to UTF-8. This behaviour needed to simply be extended to the header, i.e. the whole file.

== Pre-imp notes ==

Talked with danilo about it and we agreed that it is ok to convert the whole file to UTF-8 if necessary. Most files are UTF-8 already.

== Implmentation details ==

lib/lp/translations/utilities/gettext_po_exporter.py

 * Encode the whole file at the end instead of each chunk seperately and in different places.
 * Did away with the need of having to re-encode all chunks if the encoding changes.
 * The header is prepended at the end or the loop so that the encoding can be changed at last-minute warning.

lib/lp/translations/utilities/tests/test_gettext_po_exporter.py

 * Added test for encoding of non-ascii characters in the header.
 * Combined common code into a private method.
 * Use named format specifiers because their order changes.

== Test ==

bin/test -vvct GettextPOExporterTestCase

== Demo/QA ==

 * Import a file that has "ascii" as it's Content-type.
 * Have Danilo make a translation using ascii characters.
 * Export the file.
 * The exported file should be UTF-8 now and Данило Шеган should appear as the Last-Translator.

= Launchpad lint =

Checking for conflicts. and issues in doctests and templates.
Running jslint, xmllint, pyflakes, and pylint.
Using normal rules.

Linting changed files:
  lib/lp/translations/utilities/gettext_po_exporter.py
  lib/lp/translations/utilities/tests/test_gettext_po_exporter.py