spurious connection_read()s

[Aaron Richton <richton@nbcs.rutgers.edu>]

Somewhere between 5-10 times per day (which really isn't that often for
the load around here), slapd outputs "connection_read(%ld): no
connection!\n", i.e. from connection.c. I ran a grep with context today,
and found that invariably, these are immediately following a "closed" log
message. For example:

 conn=626905 fd=109 closed
 connection_read(109): no connection!

 conn=648575 fd=109 closed
 connection_read(109): no connection!

 conn=649607 fd=112 closed
 connection_read(112): no connection!

 conn=165899 fd=347 closed
 connection_read(347): no connection!

 conn=27471 fd=99 closed
 connection_read(99): no connection!


Why would slapd try to "connection_read" something that it apparently
knows is "closed"?

This is with 2.3.24. I haven't consciously touched LWL in production yet,
so I'm pretty sure that's not defined because it's not default yet IIRC?