[R] Output of warnings inside the source function

[Arkady Sherman]

Hello, all.
There is a problem to get an output of warnings() function to sink in a 
file specified.
There are to files

1. File "test" with content:

source("test_foo",local=T)

2. and file "test_foo" with content:

options(warn = 1)
sink("c:/temp/foo.txt",append=F)
warning("Foo warning")
warnings()
sink()

3. If I run R as

"c:\Program Files\R\rw2011\bin\R.exe" --no-save < test > out.txt

the file "c:/temp/foo.txt" will contain nothing.
But I'd like it should contain the warning message "Foo warning".
Is the behavior a bug of R or there is another way to get it working.
         Thanks in advance, Alex