Fix nptl/tst-cancel7 for non-bash shells

[Carlos O'Donell]

On Sun, Oct 28, 2012 at 9:15 PM, Rich Felker <dalias@aerifal.cx> wrote:
> This issue caused me to take a look at the implementation of system's
> handling of cancellation, which turns out to have a serious bug:
>
> http://sourceware.org/bugzilla/show_bug.cgi?id=14782
>
> It should be easy to fix; the fix is a purely-red patch (all -'s).

While your analysis looks correct the more interesting question to me
is "Why was this added in the first place?" Can you dig a bit more and
see if we can determine the reason for the deviation from the standard?
Clearly we went to a lot of work to implement the current behaviour and
I'd like to know why.

Cheers,
Carlos.