$ rm -rf d
	$ mkdir -p d/patches
	$ cd d

	$ cat > no-subject
	< Here goes a longer description of the patch, which is
	< totally useless except as a test case for the quilt mail
	< command. This paragraph is longer than 150 characters so
	< that it won't be taken for a subject header itself.
	<
	< Index: anything

	$ cat no-subject > patches/1.diff
	$ ls patches/ > series
	$ quilt mail --mbox mbox --prefix "test" --subject "This is a test" -m "Message"
	> Unable to extract a subject header from patches/1.diff

	$ cat - no-subject > patches/1.diff
	< Subject: Subject of 1.diff
	<
	< Acked-by: Dummy <dummy@some.where>
	<

	$ quilt mail --mbox mbox --prefix "test" -m "Message"
	> Introduction has no subject header

	$ cat - no-subject > patches/2.diff
	< DESC
	< Subject of 2.diff
	< is: split
	< into multiple
	< lines
	< EDESC
	<
	< Signed-off-by: Dummy <dummy@some.where>
	<

	$ cat - no-subject > patches/3.diff
	< Subject of 3.diff
	<
	< To: John X. Doe <jxd@some.where>
	<

	$ cat - no-subject > patches/4.diff
	< First paragraph used as
	< subject of 4.diff.
	<
	< Signed-off-by: Joe R. Hacker <joe@foo.baz>
	< Cc: "John X. Doe" <jxd@some.where>
	< Cc: Ü is an umlaut <used@in.german>
	<

	$ cat - no-subject > patches/5.diff
	< Subject of 1.diff
	<

	$ ls patches/ > series
	$ quilt mail --mbox mbox --prefix "test" --subject "This is a test" -m "Message"
	> Patches patches/1.diff, patches/5.diff have duplicate subject headers.

	$ cat - no-subject > patches/5.diff
	< Aw: [patch] Fwd: Re: [patch 5/7] Fw: Subject of 5.diff
	<

	$ quilt mail --mbox mbox --prefix "test" --subject "This is a test" -m "Message"
	$ grep -e '^Subject:' -e '^To:' -e '^Cc:' -e '^-- $' -e '^ ' mbox
	> Subject: [test 0/5] This is a test
	> -- 
	> Cc: Dummy <dummy@some.where>
	> Subject: [test 1/5] Subject of 1.diff
	> -- 
	> Cc: Dummy <dummy@some.where>
	> Subject: [test 2/5] Subject of 2.diff is: split into multiple lines
	> -- 
	> To: "John X. Doe" <jxd@some.where>
	> Subject: [test 3/5] Subject of 3.diff
	> To: John X. Doe <jxd@some.where>
	> -- 
	> Cc: "Joe R. Hacker" <joe@foo.baz>,
	>  "John X. Doe" <jxd@some.where>,
	>  =?UTF-8?q?=C3=9C=20is=20an=20umlaut?= <used@in.german>
	> Subject: [test 4/5] First paragraph used as subject of 4.diff.
	> Cc: "John X. Doe" <jxd@some.where>
	> Cc: Ü is an umlaut <used@in.german>
	> -- 
	> Subject: [test 5/5] Subject of 5.diff
	> -- 

	$ cd ..
	$ rm -rf d