Run tests under valgrind

Submitted by Simon McVittie

Assigned to Simon McVittie

Description

On Bug #105656, Philip suggested running the tests under valgrind. This is a larger task than one might think, because many of the tests are not fully valgrind-clean (and because valgrind doesn't currently work on Debian unstable due to binutils behaviour changes, so I'm having to test all this in a Debian 9 chroot).

I've mostly found false positives, but a couple of actual bugs.

Version: git master