unify pdb hooks for failures about twisted

[twisted-trac]

	Automation removed owner

[twisted-trac]

	@itamarst commented

#!html
<pre>
I'm talking about "post-mortem all exceptions" code. This is
currently hardcoded into twistd and trial. The code should
be unified into a startDebug() function in t.p.failure, perhaps.

</pre>

[twisted-trac]

	spiv commented

#!html
<pre>
twistd and trial share a few features... --spew is another.
 Currently, --spew's guts live in t.p.util, iirc, so that
could be another place to put it.  On the other hand, we
probably don't want t.p.util becoming a dumping ground for
any old miscellaneous crap we can't be bothered categorising
properly :)

&lt;wild speculation>
It's interesting how both twistd and trial are programs that
run code passed to it on the command-line.  Perhaps they
could share more implementation?
&lt;/wild speculation>

</pre>

[twisted-trac]

	@itamarst commented

#!html
<pre>
Indeed. And when we have a NT service equivalent of twistd
this will be a third instance.

</pre>