test: Don't strip portions of test name after '-' for temporary files.

We have test names like maildir-sync now, so it's cleaner if the
temporary files created are named things like maildir-sync-10.out
rather than maildir-10.out. Presumably the extra stripping here came
from naming conventions in git's test suite.

test/test-lib.sh

@@ -909,7 +909,6 @@ EOF
 cd -P "$test" || error "Cannot setup test environment"
 
 this_test=${0##*/}
-this_test=${this_test%%-*}
 for skp in $NOTMUCH_SKIP_TESTS
 do
 	to_skip=