mailinfo: support format=flowed

Add best-effort support for patches sent using format=flowed (RFC 3676).
Remove leading spaces ("unstuff"), remove soft line breaks (indicated
by space + newline), but leave the signature separator (dash dash space
newline) alone.

Warn in git am when encountering a format=flowed patch, because any
trailing spaces would most probably be lost, as the sending MUA is
encouraged to remove them when preparing the email.

Provide a test patch formatted by Mozilla Thunderbird 60 using its
default configuration.  It reuses the contents of the file mailinfo.c
before and after this patch.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 19 insertions, 0 deletions

diff --git a/t/t4256-am-format-flowed.sh b/t/t4256-am-format-flowed.sh
new file mode 100755
index 0000000000..6340310e9a
--- /dev/null
+++ b/t/t4256-am-format-flowed.sh
@@ -0,0 +1,19 @@
+#!/bin/sh
+
+test_description='test format=flowed support of git am'
+
+. ./test-lib.sh
+
+test_expect_success 'setup' '
+	cp "$TEST_DIRECTORY/t4256/1/mailinfo.c.orig" mailinfo.c &&
+	git add mailinfo.c &&
+	git commit -m initial
+'
+
+test_expect_success 'am with format=flowed' '
+	git am <"$TEST_DIRECTORY/t4256/1/patch" >stdout 2>stderr &&
+	test_i18ngrep "warning: Patch sent with format=flowed" stderr &&
+	test_cmp "$TEST_DIRECTORY/t4256/1/mailinfo.c" mailinfo.c
+'
+
+test_done