[PATCH 1/1] send-email: allow to compose only prepared cover letter

Since @rev_list_opts contains everything that goes to the git format-patch
including an additional option like '--cover-letter' we might be interested to
compose it before send.

My often use case is to do:
	% git format-patch --cover-letter --subject-prefix="PATCH vN" rev1^..revXYZ
	% $GIT_EDITOR 0000-*
	% git send-email 00* # assumes series less than 100 patches
	% rm -f 00*

Since git-send-email may send directly from repository it would be nice to
reduce above to just
	% git send-email --compose --cover-letter --subject-prefix="PATCH vN" rev1^..revXYZ

P.S. Going further we can even introduce something like --valid-cmd to
send-email to run, for example, checkpatch.pl.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 git-send-email.perl | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/git-send-email.perl b/git-send-email.perl
index e3ff44b..fc62d28 100755
--- a/git-send-email.perl
+++ b/git-send-email.perl

@@ -631,7 +631,10 @@ sub get_patch_subject {
 	die "No subject line in $fn ?";
 }
 
-if ($compose) {
+if ($compose and @rev_list_opts and grep { $_ eq '--cover-letter' } @rev_list_opts) {
+	# Cover letter always goes first
+	do_edit($files[0]);
+} elsif ($compose) {
 	# Note that this does not need to be secure, but we will make a small
 	# effort to have it be unique
 	$compose_filename = ($repo ?

-- 
2.5.3