IOExts.slurpFile fails on zero-length files

[George Russell]

Specifically I get 

*** Exception: invalid argument
Action: hGetBuf
Handle: {loc=/tmp/d,type=readable,binary=False,buffering=block (8192)}
Reason: illegal buffer size 0

whether using 5.03.2 on Solaris or 5.03.20020410 on Linux.