pygettext uses non-standard timestamp format in the POT-Creation-Date field. For example:

POT-Creation-Date: 2013-06-03 22:31+CEST

whereas xgettext uses this format:

POT-Creation-Date: 2013-06-03 22:31+0200

You could use this code to generate timestamps in the same format as xgettext:

from time import time, localtime, strftime
from calendar import timegm

def gettext_timestamp():
    now = int(time())
    nowtuple = localtime(now)
    offset = timegm(nowtuple) - now
    sign = '-' if offset < 0 else '+'
    hour, minute = divmod(abs(offset) // 60, 60)
    return strftime('%Y-%m-%d %H:%M', nowtuple) + sign + '%02d%02d' % (hour, minute)

It's probably worth changing.  My only concern would be backwards compatibility issues.

I'm going to be adding some tests around pygettext tool and then tackling this.

Patch File iss18128.patch adds test_i18n to start testing the entire Tools/i18n package, and has a very simple fix.

Post-review - new patch

Barry, would you be OK with just applying this to 3.5?  We can add a porting note to whatsnew.  My guess, though, is that no one is going to notice.

Oh, I forgot to say that the patch looks good to me.

@rdm: I'm pretty sure you're right about nobody noticing. :)  Make it so!

New changeset c969413584cf by R David Murray in branch 'default':
#18128: use standard +NNNN timezone format in POT-Creation-Date header.
https://hg.python.org/cpython/rev/c969413584cf

Thanks, Michael.