[Dovecot] dovecot imap auth fails to reconnect pgsql backend

[Frank Wang]

> Another possibility would be to attach gdb to the running dovecot-auth  
> process:
> 
> gdb -p `dovecot-auth`
> cont
> <wait for crash>
> bt full
> 
(gdb) cont
Continuing.

Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread -1208469824 (LWP 27503)]
0x080619e6 in passdb_cache_init ()
(gdb) bt full
#0  0x080619e6 in passdb_cache_init ()
No symbol table info available.
#1  0x00128c0f in ?? () from /usr/lib/dovecot/auth/libdriver_pgsql.so
No symbol table info available.
#2  0x0806dff0 in io_loop_handler_run ()
No symbol table info available.
#3  0x0806d0d8 in io_loop_run ()
No symbol table info available.
#4  0x0805a3b7 in main ()
No symbol table info available.