backglue.c sometimes falsely returns LDAP_SIZELIMIT_EXCEEDED (ITS#2888)

[rhafer@suse.de]

Full_Name: Ralf Haferkamp
Version: 2.1.25 (guess HEAD too)
OS: SuSE Linux 9.0
URL: ftp://ftp.openldap.org/incoming/
Submission from: (NULL) (212.95.107.74)


I have a setup similar to this: 

database ldap
uri "ldap://10.0.0.1/";
subordinate
suffix          "ou=people,dc=example,dc=com"

database        ldbm
cachesize       3000
directory       /var/lib/ldap
lastmod         on
mode            0600
suffix          "dc=example,dc=com"

If I do the following in search:
ldapsearch -x  uid=testuser -b "dc=example,dc=com" -z 1

The server returns one entry and the errorcode LDAP_SIZELIMIT_EXCEEDED. Even
though the whole tree (the ldbm database and subordinate ldap database) contain
only one entry which matches the filter. Search without "-z 1" also returns only
this one entry and LDAP_SUCCESS (which is correct).