Do not hardlink symlink assets

Issue: https://progress.opensuse.org/issues/129340

Hardlinking a symlink will only work if the link is absolute, and
we would have to check that recursively if the symlink target
itself is a symlink, so just fall back to symlink then.

lib/OpenQA/Worker/Engines/isotovideo.pm

@@ -176,10 +176,16 @@ sub _link_asset ($asset, $pooldir) {
     # Try to use hardlinks first and only fall back to symlinks when that fails,
     # to ensure that assets cannot be purged early from the pool even if the
     # cache service runs out of space
-    eval { link($asset, $target) or die qq{Cannot create link from "$asset" to "$target": $!} };
-    if (my $err = $@) {
+    # If the given asset is a symlink itself, to not hardlink a symlink
+    my $linked = 0;
+    unless (-l $asset) {
+        $linked = eval { link($asset, $target) or die qq{Cannot create link from "$asset" to "$target": $!} };
+        if (my $err = $@) {
+            log_debug(qq{Symlinking asset because hardlink failed: $err});
+        }
+    }
+    unless ($linked) {
         symlink($asset, $target) or die qq{Cannot create symlink from "$asset" to "$target": $!};
-        log_debug(qq{Symlinked asset because hardlink failed: $err});
     }
     log_debug(qq{Linked asset "$asset" to "$target"});