no-xmailer tests fail under Mac OS

Failures start from

commit d2384abff7a6181fd7b9a51af7e780aa21e5cb8d (refs/bisect/bad)
Author: Luis Henriques [off-list ref]
Date:   Thu Dec 4 19:11:30 2014 +0000

    test/send-email: --[no-]xmailer tests

    Add tests for the --[no-]xmailer option.

    Signed-off-by: Luis Henriques [off-list ref]
    Signed-off-by: Junio C Hamano [off-list ref]

but continue with Junio's SQUASH??? commit at b728d078

Verbose output follows

expecting success:
do_xmailer_test 1 "--xmailer" &&
do_xmailer_test 0 "--no-xmailer"

0001-add-master.patch
not ok 109 - --[no-]xmailer without any configuration
#
# do_xmailer_test 1 "--xmailer" &&
# do_xmailer_test 0 "--no-xmailer"
#

expecting success:
test_config sendemail.xmailer true &&
do_xmailer_test 1 "" &&
do_xmailer_test 0 "--no-xmailer" &&
do_xmailer_test 1 "--xmailer"

0001-add-master.patch
not ok 110 - --[no-]xmailer with sendemail.xmailer=true
#
# test_config sendemail.xmailer true &&
# do_xmailer_test 1 "" &&
# do_xmailer_test 0 "--no-xmailer" &&
# do_xmailer_test 1 "--xmailer"
#

expecting success:
test_config sendemail.xmailer false &&
do_xmailer_test 0 "" &&
do_xmailer_test 0 "--no-xmailer" &&
do_xmailer_test 1 "--xmailer"

0001-add-master.patch
not ok 111 - --[no-]xmailer with sendemail.xmailer=false
#
# test_config sendemail.xmailer false &&
# do_xmailer_test 0 "" &&
# do_xmailer_test 0 "--no-xmailer" &&
# do_xmailer_test 1 "--xmailer"
#

# failed 3 among 111 test(s)
1..111