archival: don't set gzip filename header when there's no filename
This mainly affects hgweb, which can generate tar.gz archives without
filenames. Without this change, the header would be set to ".gz",
which can confuse Safari into extracting the file and renaming it to
"gz" when "Open 'safe' files after downloading" is enabled.
file(1) before:
hg-crew-5e51254ad4d4.tar.gz: gzip compressed data, was ".gz", last modified: Thu Dec 2 11:46:20 2010, max compression
after:
hg-crew-5e51254ad4d4.tar.gz: gzip compressed data, last modified: Thu Dec 2 11:46:20 2010, max compression
% Without -v
access log created - .hg/hgrc respected
% errors
% With -v
listening at http://localhost/ (bound to 127.0.0.1:HGPORT1)
% errors
% With -v and -p HGPORT2
listening at http://localhost/ (bound to 127.0.0.1:HGPORT2)
% errors
% With -v and -p daytime (should fail because low port)
abort: cannot start server at 'localhost:13': Permission denied
abort: child process failed to start
% errors
% With --prefix foo
listening at http://localhost/foo/ (bound to 127.0.0.1:HGPORT1)
% errors
% With --prefix /foo
listening at http://localhost/foo/ (bound to 127.0.0.1:HGPORT1)
% errors
% With --prefix foo/
listening at http://localhost/foo/ (bound to 127.0.0.1:HGPORT1)
% errors
% With --prefix /foo/
listening at http://localhost/foo/ (bound to 127.0.0.1:HGPORT1)
% errors