[BUG] git archive formats and dashdash

--format option of git archive stops working if -- is used:

Shell session:
----------------
$ git archive -o test3.zip --format=zip master -- exec_cmd.c
$ file test3.zip
test3.zip: POSIX tar archive

# Eh...

$ git archive -o test4.zip --format=zip master exec_cmd.c
$ file test4.zip
test4.zip: Zip archive data, at least v1.0 to extract

# That worked.

----------------

The bug seems to be in that archive appends the --format
option to its arguments, not taking into account that there
may be -- before that point, disabling option interpretation.

Git version 1.6.6-rc2

-Ilari