A little update on the StringTest failures on 32-bit systems. This was already reported upstream by thopiekar: https://github.com/Ultimaker/CuraEngine/issues/619 I linked the sid build results there.
For some very strange reason, I don't see this SEGFAULT when I run the build process in a 32-bit VM on an amd64 system. Valgrind doesn't report any errors either.