Description of problem:
nsslapd-defaultnamingcontext does not change when the assigned suffix got
deleted.

Version-Release number of selected component (if applicable):
389-ds-base-1.3.8.4-9.el7.x86_64


How reproducible:
Always

Steps to Reproduce:
1. Add a test suffix - "dc=test2,dc=com"

2. Assign the test suffix to the nsslapd-defaultnamingcontext
ldapmodify -x -h localhost -p 389 -D "cn=Directory Manager"  -w Secret123 <<
EOF
dn: cn=config
changetype: modify
replace: nsslapd-defaultnamingcontext
nsslapd-defaultnamingcontext: "dc=test2,dc=com"
EOF

3. delete the suffix :
ldapdelete -x -r -h localhost -p 389 -D "cn=Directory Manager"  -w Secret123
"dc=test,dc=com"

4. Check the value of nsslapd-defaultnamingcontext, it is still the same suffix
which is already deleted.
ldapsearch -x -h localhost -p 389 -D "cn=Directory Manager"  -w Secret123 -b
"cn=config" | grep -i "nsslapd-defaultnamingcontext"
nsslapd-defaultnamingcontext: dc=test,dc=com


Expected results:
Either nsslapd-defaultnamingcontext should be blank OR it should have the other
existing suffix as its value.