mod_debug_traceback: Remove direct POSIX signal handling, require Prosody 0.12+
Hooking an event is safer than directly hooking signals
For context see Prosody trunk rev 69faf3552d52
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summary: External Service Discovery
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This module implementing [XEP-0215] is included with Prosody 0.12 but made available here for older versions.
Documentation is available on the [Prosody site][doc:modules:mod_external_services].