[Rd] no internal function "int.unzip" in R 2.9 on Windows

[audrey at ebi.ac.uk]

Dear list,

Using R 2.9, I have the following error on Windows when I try using
.Internal(int.unzip(...)):

> .Internal(int.unzip("test.zip",NULL, "."))
Error in .Internal(int.unzip("test.zip", NULL, ".")) :
  no internal function "int.unzip"

The same error also happens with R 2.10 but not on R 2.8. And it does not
happen with R 2.9 on Mac or Unix.
I have googled the error message but cannot find much.

Does anyone know if the way R calls unzip functions on Windows has changed
and if this is permanent?
I am sorry if I miss something obvious, but any suggestions on how I can
fix the problem?
I want to keep using int.unzip and not the utils function unzip because I
use its output afterwards in my script.

Best wishes,
Audrey