LDAPReference to directories with identical search base DN do not check DN consistency at modification time

Suppose you have both a userDirectory and a groupsDirectory configured to use the same search base DN dc=example,dc=com and the LDAPReference configured as usual for the fields members and subGroups with forceDnConsistencyCheck set to true.

When editing the list of members of a group, the list of subGroups gets erased since because the current implementation of LDAPReference does not enforce DN consitency checks at write time (only at fetch time).