Comment 7 for bug 1615757

The dpkg output from comment #6 isn't relevant, since that didn't have all the special preloading setup in place.

Adding a bit more debugging to click's preload shim (now in lp:click/devel) reveals:

Error getting address of symbol 'mknod': /home/cjwatson/src/ubuntu/click/click/preload/.libs/libclickpreload.so: undefined symbol: mknod

So it seems that this must be due to glibc changes, although I'm a bit baffled how that could be since xenial's libc doesn't seem to have a 'mknod' symbol either and none of the changes in the diff appear relevant. Maybe we were accidentally overloading a mknod from some other library? Not sure. Perhaps it's the overlap of several toolchain changes. Anyway, preloading __xmknod instead fixes it; it's a bit nasty, but no worse than the stuff we already do with __xstat.