Some shells set $_ to an absolute path.
[tinc] / test /
drwxr-xr-x   ..
-rw-r--r-- 119 Makefile.am
-rwxr-xr-x 315 basic.test
-rwxr-xr-x 114 executables.test
-rwxr-xr-x 599 sptps_basic.test
-rw-r--r-- 606 testlib.sh