Report mails arriving with content-type: application/octet-stream

A Fedora user is reporting (in a ticket that's a couple of years old
now) that when the system locale is set to de_DE.UTF-8, the report
emails may, for the month of March, arrive with the content-type set to
application/octet-stream.
https://bugzilla.redhat.com/show_bug.cgi?id=1317122

It seems that the Amanda:Report::human::print_header() function will
call POSIX::strftime() and depending on various things I don't
understand, will produce non-UTF8 output on Fedora (I tested back to
Fedora 23).  But it's OK on RHEL7.  I grabbed the strftime example from
perldoc POSIX and ran it:

LANG=de_DE.utf8 perl -MPOSIX -e 'print POSIX::strftime( "%A, %B %d, %Y", 0, 0, 0, 19, 2, 95, 2 ), "\n";'

On F27: Sonntag, M�rz 19, 1995
On EL7: Dienstag, März 19, 1995

Hopefully that won't get mangled in transit.  Basically, the F27 result
is not actually utf8.  I don't even want to get into why the days of
the week are different.

Now, if I use binmode to set stdout to utf8:

LANG=de_DE.utf8 perl -MPOSIX -e 'binmode(STDOUT, ":utf8"); print POSIX::strftime( "%A, %B %d, %Y", 0, 0, 0, 19, 2, 95, 2 ), "\n";'

On F27: Sonntag, März 19, 1995
On EL7: Dienstag, März 19, 1995

Again, if that gets mangled, the EL7 version is now broken.

I haven't paid any attention to what's happened in the Perl world in the
last decade so I have no idea if there's a good explanation for this or
if there is a way to write code that's compatible across versions.

So in Fedora we'll probably solve this by patching amreport to call
binmode as above, assuming that the reporter confirms that it works.
But one other solution is to just force the locale to 'C', either at the
top of the script or around the strftime call in
Amanda:Report::human::print_header().  Since the report itself isn't
going to be translated to the local language, it seems odd that the date
would be translated.

 - J<