ommiting header causes multibyte errors

[Ariel]

I'm trying to generate a .po file containing UTF-8 using --from-code=UTF-8

If I run xgettext with --omit-header it gives errors:

warning: The following msgid contains non-ASCII characters. This will 
cause problems to translators who use a character encoding different from 
yours. Consider using a pure ASCII msgid instead.

And a bunch of:
invalid multibyte sequence


If I let it output the header it works fine.


If I omit the header, it's my responsibility to specify charset, etc. 
elsewhere. xgettext should not assume it suddenly because ASCII.

For example:

Say I wanted to cat a bunch of .po files together, so I don't want a 
header.

Or the reason listed in the manual of removing a source of variance.

Or, in my case because I msgmerge to a file that already has a header, and 
I want it exactly like that, without Report-Msgid-Bugs-To and 
POT-Creation-Date.

It doesn't really matter why - omitting a header does not mean the file is 
now ascii.

        -Ariel

PS. I'm not subscribed to the list (although I check the archives), please 
CC me.