DnD to category fails if it is home category of one selected item

Description

Steps to reproduce:

1. Have category C1 with entry E1,and category C2 with entry E2.
2. Link E1 to C2.
3. View C2. It now contains E1 and E2.
4. Select E1 and E2 and try to DnD to C1.

Expected:
Can DnD and move items to C1, by which E2 is re-linked to C1, and E1 (which already has a link to C1) is unlinked from C2.
Actual: Action prevented.

Note: The triggering factor preventing this operation is that E1 has C1 as home category. Consider this very similar scenario which works as expected:

1. Have category C1 empty, C2 with Entry E1 and E2.
2. Link E1, E2 to C1.
3. Select E1 and E2 in C2 and try to DnD to C1.
Result: Can successfully DnD and move items to C1, by which both E1 and E2 are unlinked from C2 (already linked to C1).