`parseGetText` can't parse zope.app catalogs (fr and zh_CN)

[tseaver]

In https://bugs.launchpad.net/zope.i18n/+bug/356004, Devin (devin@charityfinders.org) reported:

When I attempt to use GettextImportFilter to parse the gettext translation catalogs in zope.app for fr and zh_CN, I get the following tracebacks (the first is fr, the second is zh_CN):

Traceback (most recent call last):
  File "./generate-pillar-domain.py", line 68, in main
    filter.importMessages(language, fp)
  File "/usr/lib/python2.5/site-packages/zope/app/i18n/filters.py", line 95, in importMessages
    result = parseGetText(file.readlines())[3]
  File "/usr/lib/python2.5/site-packages/zope/app/i18n/filters.py", line 197, in parseGetText
    raise ParseError(3, pointer + 1)
ParseError: state 3, line 4382

Traceback (most recent call last):
  File "./generate-pillar-domain.py", line 68, in main
    filter.importMessages(language, fp)
  File "/usr/lib/python2.5/site-packages/zope/app/i18n/filters.py", line 95, in importMessages
    result = parseGetText(file.readlines())[3]
  File "/usr/lib/python2.5/site-packages/zope/app/i18n/filters.py", line 197, in parseGetText
    raise ParseError(3, pointer + 1)
ParseError: state 3, line 268

Both errors occur when a blank line is found at the beginning of a msgstr portion in a gettext file.

and later:

Just to clarify, when I say "blank line", I mean "quoted empty string".