Variable triggers global destruction hang

saintmike has asked for the wisdom of the Perl Monks concerning the following question:

The following code snippet terminates ok:

    open FH , "| cat " ;
    open STDOUT, ">&FH";
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but if you add a variable holding a regular expression, like

    my $foo = qr(a);
    open FH , "| cat " ;
    open STDOUT, ">&FH";
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then this code hangs, according to strace while waiting for the forked process to terminate:

...
rt_sigaction(SIGQUIT, {SIG_IGN}, {SIG_DFL}, 8) = 0
    waitpid(29096, ...
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Is this a known perl bug?