[Rd] gctorture() and gzfile() doesn't get along.

[Hin-Tak Leung]

Found the simpliest way of seeing I bug I encountered doing "R CMD check --use-gct": Just launch R (with --vanilla), and do this:

> ?gctorture
# this work
> gctorture()
> ?gctorture
Error in gzfile(file, "rb") : 
  can only weakly reference/finalize reference objects
# this does not


It seems that when gctorture() is on gzfile() doesn't work.