The Tcl_OpenFileChannel API call trashes memory
when feeded with NULL interp. The workaround was
to open the file using standard open() and then
do Tcl_MakeFileChannel() using the resulting OS handle.
This was observed on Linux, Solaris and Darwin. I havent
tested it on Windows.
Interestingly, Purify on Solaris can't pinpoint anything.
I assume the problem lies somewhere in the new path