This is valgrind upsteam bug https://bugs.kde.org/show_bug.cgi?id=508145
Fix now also committed on the VALGRIND_3_25_BRANCH: https://sourceware.org/cgit/valgrind/commit/?h=VALGRIND_3_25_BRANCH The VALGRIND_3_25_BRANCH contains a couple of backports that didn't make it to the last stable release yet (last release is 3.25.1).
