git-am: use printf instead of echo on user-supplied strings
Under some implementations of echo (such as that provided by dash), backslash escapes are recognized without any other options. This means that echo-ing user-supplied strings may cause any backslash sequences in them to be converted. Using printf resolves the ambiguity.
This bug can be seen when using git-am to apply a patch whose subject contains the character sequence "\n"; the characters are converted to a literal newline. Noticed by Szekeres Istvan.
Signed-off-by: Jeff King <firstname.lastname@example.org> Signed-off-by: Junio C Hamano <email@example.com>