Message 74942 - Python tracker

IIUC, another error return value (besides -1) is PATH_MAX, meaning that
the buffer would overrun; correct me if I'm wrong. If I'm not, I propose
that they get handles similarly.

In addition, it might be safer to compare to (size_t)-1 (I keep
forgetting whether this is the default when comparing signed and
unsigned - some compilers warn about comparisong with mixed signs).