Jeff King authored May 26, 2011 and Junio C Hamano committed May 26, 2011

In older versions of git, we used rfc822 header folding to
indicate that the original subject line had multiple lines
in it.  But since a1f6baa5

 (format-patch: wrap long header
lines, 2011-02-23), we now use header folding whenever there
is a long line.

This means that "git am" cannot trust header folding as a
sign from format-patch that newlines should be preserved.
Instead, format-patch needs to signal more explicitly that
the newlines are significant.  This patch does so by
rfc2047-encoding the newlines in the subject line. No
changes are needed on the "git am" end; it already decodes
the newlines properly.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>