Possible bug in sort 5.97

[address@hidden]

Hello there.
I think I have noticed a bug in 'sort' program, version 5.97.
When I try to sort a non-empty file and I redirect the input
to the same file as follows

$ sort testfile > testfile

the file suddenly gets empty. I think the program should sort
the file and
redirects the file sorted to itself. Although the operation
has no sense, I think this could cause a disaster if I
mismatch when typing the ouput file.
Other programs like 'cat' warns me if the input file is the
same as output, and cancels the operation.