Redmine

We're working with parent issues a lot and we're facing an odd bug:

Let's imagine the following situation:

• Issue #1 is the main issue for a feature
• Issue #2 and #3 shall be sub-issues of issue #1
• Issue #2 and #3 shall have a relation to each other (don't question that ;-)

Open up issue #2 and assign issue #1 as parent task.
Then add ticket #3 as normal ticket relation to ticket #2.

Then open up ticket #3 and try to assign issue #1 as parent task.
This won't work unless I remove the relation between issues #2 and #3
Action fails with error "Parent task is invalid"

After removing the relation between issues #2 and #3 I can assign issue #1 as parent task to #3.
I would expect redmine to be able to also assign #1 as parent task to #3 also if #3 yet has a relation to #2 which is yet a sub issue of #1

Then, after having figured out that behaviour I would have expected that I can't re-add the relation between issues #2 and #3 – but yes, that's possible.

Wow - this sounds weird, but it's reproducable!
Tested with 2.5.2 and current trunk.