test-meta.sh: remove a bashism, and don't delete dirs on exit.

It's really annoying to have it wiping out directories that you want to
examine after a failed test.  And "set -o pipefail" is not available in the
version of bash on MacOS 10.4.

Signed-off-by: Avery Pennarun <apenwarr@gmail.com>

t/test-meta.sh

@@ -1,6 +1,5 @@
 #!/usr/bin/env bash
 . wvtest.sh
-set -e -o pipefail
 
 TOP="$(pwd)"
 export BUP_DIR="$TOP/buptest.tmp"
@@ -186,7 +185,4 @@ then
   )
 fi
 
-force-delete "${BUP_DIR}"
-force-delete "$TOP/bupmeta.tmp"
-
 exit 0