We see a build failures in ptests for valgrind on some hosts but not on all hosts. The reason is xmllint tries to find DTD files either locally or reaches out over network to download them in-promptu. This fails then after recently where network access is barred in non-fetchable tasks by default, a workaround is https://git.yoctoproject.org/poky/commit/?id=f1af0c1f97cfb58017191ba9c703178270307213 but we should investigate why it works on some hosts and fails on some. Perhaps there is a unknown host dependency which is responsible for this.
Perhaps adding dependency in ptest case will allow dropping work-around patch.