fix(issue #1219): Exception raised if the revision date is blank

[arunsoman]

Fixes #1219

What

autonomous fix via atomic-forge fix — CIE (code graph over MCP) localized the bug, generated a failing regression test, and forge's repair loop fixed the source against it.

Issue

Exception raised if the revision date is blank

I created a .po file with Poedit and it left the PO-Revision-Date field blank in the header. pybabel (2.17.0) raises the following exception when updating or compiling the po file:

 File "C:\<>\Python312\Lib\site-packages\babel\messages\catalog.py", line 102, in _parse_datetime_header
    dt = datetime.datetime.strptime(match.group('datetime'), '%Y-%m-%d %H:%M')
         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\<>\Python312\Lib\_strptime.py", line 554, in _strptime_datetime
    tt, fraction, gmtoff_fraction = _strptime(data_string, format)
                                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\<>\Python312\Lib\_strptime.py", line 333, in _strptime
    raise ValueError("time data %r does not match format %r" %
ValueError: time data '' does not match format '%Y-%m-%d %H:%M'

It would be nice to ignore the blank date, or at least, to give a graceful warning/error message.

How it was verified

• regression test: tests/test_forge_1219.py (CIE-generated; fails on the pre-fix code, passes on the fix)
• repair rounds: 1 failures: 2 -> 0
• repaired file(s): babel/messages/catalog.py

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🏛️ Generated end-to-end by atomic-forge — an autonomous, test-driven issue→PR repair engine (atomic-forge fix <issue-url>).