ImportMode REPLACE vs IdConflictPolicy LEGACY vs stashing

Consider this case:

• existing node "/tmp/x" in repo with UUID x1 and mixin type xm that requires a child node "/tmp/x/child"
• package import with IdConflictPolicy.LEGACY and ImportMode REPLACE (default). Package contains /tmp/x" with UUID x2 (!= x1) and does not have the mixin type xm, nor the child node required by it

Import detects UUID present in package and on node to be updated, decides to stash it. New node is created, child nodes are moved back from stashed node, but properties are not (due to ImportMode REPLACE), thus the mixin type is not re-added. Import fails.

Either we should restore the mixin type, or we should not restore the child that is only allowed by that mixin type.

(This is a change in behavior introduced by JCRVLT-551)