Argentina, Brazil, Mauritius, Syria).

recursion when we are unable to convert a localized error message to the
client's encoding.  We've been over this ground before, but as reported by
Ibrar Ahmed, it still didn't work in the case of conversion failures for
the conversion-failure message itself :-(.  Fix by installing a "circuit
breaker" that disables attempts to localize this message once we get into
recursion trouble.

Patch all supported branches, because it is in fact broken in all of them;
though I had to add some missing translations to the older branches in
order to expose the failure in the particular test case I was using.

address of afterTriggers->query_stack[afterTriggers->query_depth] and hung
onto it through all its firings of triggers.  However, if a trigger causes
sufficiently many nested query executions, query_stack will get repalloc'd
bigger, leaving AfterTriggerEndQuery --- and hence afterTriggerInvokeEvents
--- using a stale pointer.

So far as I can find, the only consequence of this error is to stomp on a
couple of words of already-freed memory; which would lead to a failure only if
that chunk had already gotten re-allocated for something else.  So it's hard
to exhibit a simple failure case, but this is surely a bug.

I noticed this while working on my recent patch to reduce pending-trigger
space usage.  The present patch is mighty ugly, because it requires making
afterTriggerInvokeEvents know about all the possible event lists it might get
called on.  Fortunately, this is only needed in back branches because CVS HEAD
avoids the problem in a different way: afterTriggerInvokeEvents only touches
the passed AfterTriggerEventList pointer once at startup.  Back branches are
stable enough that wiring in knowledge of all possible call usages doesn't
seem like a killer problem.

Back-patch to 8.0.  7.4's trigger code is completely different and doesn't
seem to have the problem (it doesn't even use repalloc).

Patch from Sushant Sinha <sushant354@gmail.com>
http://archives.postgresql.org/pgsql-hackers/2008-07/msg00785.php

according to the TupleDesc's natts, not the number of physical columns in the
tuple.  The previous coding would do the wrong thing in cases where natts is
different from the tuple's column count: either incorrectly report error when
it should just treat the column as null, or actually crash due to indexing off
the end of the TupleDesc's attribute array.  (The second case is probably not
possible in modern PG versions, due to more careful handling of inheritance
cases than we once had.  But it's still a clear lack of robustness here.)

The incorrect error indication is ignored by all callers within the core PG
distribution, so this bug has no symptoms visible within the core code, but
it might well be an issue for add-on packages.  So patch all the way back.