Fix m2 regression test.

This is not really a good test as the behaviour for /c is unspecified.

For the record, ksh93 returns:

$ printf "abc\n\cdef"
abc
ef$

Discussed with:	Garret D'Amore (Illumos)
MFV 266913+266914:

3897 zfs filesystem and snapshot limits (fix leak)
4901 zfs filesystem/snapshot limit leaks

MFC after:	3 days