tests: add outside bind mounts to 75_hooks

it may happen, that someone bind mounts manually or via an immutable setup the tomb mountdir somewhere else.
Tomb should be able to discover such mounts and close them if the tomb itself is closed.

extras/test/75_hooks.sh

@@ -1,6 +1,6 @@
 #!/usr/bin/env zsh
 
-export test_description="Testing tomb bind hooks"
+export test_description="Testing tomb bind hooks & mounts"
 
 TEMPHOME=$HOME
 
@@ -18,13 +18,23 @@ test_expect_success 'Testing bind hooks' '
     tt_close &&
     touch "$TEMPHOME/$bindtest" &&
     tt_open --tomb-pwd $DUMMYPASS &&
-	echo "$RND" &&
-	cat "$TEMPHOME/$bindtest" &&
+    echo "$RND" &&
+    cat "$TEMPHOME/$bindtest" &&
     tt list $testname &&
     tt_close
     '
 
     # RND2=$(cat "$TEMPHOME/$bindtest") &&
     # [[ "$RND" = "$RND2" ]] &&
 
+test_expect_success 'Testing outside bind mounts' '
+    tt_open --tomb-pwd $DUMMYPASS &&
+    tt_set_ownership "$MEDIA/$testname" &&
+    sudo mkdir "$MEDIA/$testname-bind" &&
+    sudo mount --bind "$MEDIA/$testname" "$MEDIA/$testname-bind" &&
+    tt list $testname &&
+    tt_close &&
+    sudo rmdir "$MEDIA/$testname-bind"
+    '
+
 test_done