[ Reason ]
Fix Bug #1137653. Build failure due to flaky test. There are also
failures for the same test in ci.debian.org.

[ Impact ]
Anybody trying to build the package may find that it fails due to the flaky test.

[ Tests ]
I've tested that the fixed package builds ok where it used to fail.

[ Risks ]
Very low. No real code changes. Only a test has been disabled.

[ Checklist ]
   [X] *all* changes are documented in the d/changelog
   [X] I reviewed all changes and I approve them
   [X] attach debdiff against the package in (old)stable
   [X] the issue is verified as fixed in unstable

[ Changes ]
Disable "test_dont_crash_on_handshake_timeout".

[ Other info ]
Package is already uploaded.