tests: fix and add lint for non-portable seq

diff --git a/t/t9300-fast-import.sh b/t/t9300-fast-import.sh
index f8f869e26a4caf7ec10f6f7f0c447b0cd179d9e6..40fe7e49767ac4e0bbe5686413ff2b667171747a 100755 (executable)
--- a/t/t9300-fast-import.sh
+++ b/t/t9300-fast-import.sh
@@ -3144,7 +3144,10 @@ background_import_then_checkpoint () {
        echo $! >V.pid
        # We don't mind if fast-import has already died by the time the test
        # ends.
-       test_when_finished "exec 8>&-; exec 9>&-; kill $(cat V.pid) || true"
+       test_when_finished "
+               exec 8>&-; exec 9>&-;
+               kill $(cat V.pid) && wait $(cat V.pid)
+               true"
 
        # Start in the background to ensure we adhere strictly to (blocking)
        # pipes writing sequence. We want to assume that the write below could