Seems to work in my tests. Could you do a bit more with gdb:
#6 0x0812e512 in client_dict_connect (dict=0x819abc8) at /var/tmp/dovecot-1.1.rc6/src/lib-dict/dict-client.c:268 query = 0x8178664 "D\206\027\b\003"
fr 6 p *dict
Program terminated with signal 11, Segmentation fault.
#0 0xfed0578c in strlen () from /lib/libc.so.1
(gdb) fr 6
#6 0x0812e512 in client_dict_connect (dict=0x819abc8)
at /var/tmp/dovecot-1.1.rc6/src/lib-dict/dict-client.c:268
268 dict->value_type, dict->username,
dict->uri);
Current language: auto; currently minimal
(gdb) p *dict
$1 = {dict = {name = 0x8163b6c "proxy", v = {
init = 0x812e640