sharness: t0030-mount test_must_fail fails on osx

[jbenet]

on osx, i get this:

'output' is not empty, it contains:
must fail: ipfs mount -f=not_ipfs -n=not_ipns
not ok 7 - 'ipfs mount' output looks good
#
#       test_must_be_empty output &&
#       test_should_contain "not_ipns\|not_ipfs" output.err
#

from

test_expect_success "'ipfs mount' fails when there is no mount dir" '
    test_must_fail ipfs mount -f=not_ipfs -n=not_ipns >output 2>output.err
'

test_expect_success "'ipfs mount' output looks good" '
    test_must_be_empty output &&
    test_should_contain "not_ipns\|not_ipfs" output.err
'

on linux this seems to be fine. it seems that the stdout of test_must_fail is what is going to output, not the stdout of ipfs mount -f=not_ipfs -n=not_ipns. perhaps needs some grouping there.

we haven't noticed all these because FUSE is disabled on travis! :(

[jbenet]

Fixed in #1112