EPIPE not ignored when shutting down test servers (on gentoo)

[Vincent Ladeuil]

5 selftest failures with bzr.dev reno 5398:
    * bzrlib.tests.blackbox.test_check.ChrootedCheckTests.test_check_missing_branch
    * bzrlib.tests.test_bzrdir.TestHTTPRedirections_urllib.test_loop
    * bzrlib.tests.test_http.TestBadStatusServer.test_http_has(urllib,HTTP/1.0)
    * bzrlib.tests.per_branch.test_branch.ChrootedTests.test_open_containing(BranchReferenceFormat)
    * bzrlib.tests.per_controldir.test_controldir.ChrootedControlDirTests.test_find_repository_no_repository(BzrDirMetaFormat1)

See http://babune.ladeuil.net:24842/job/selftest-gentoo/166/testReport/?

This is a, not surprising, variation from other platforms and is tests specific.

I'll have a patch shortly.