Pet/Movement: PetAI interrupts movement spells when not in combat

Description:

Current behaviour:

When the player is casting a pet spell which would move the pet to a enemy (not in combat with the enemy), the pet will start the movement and immediatley follow his master again.

As Example:
A Unholy Deathknight with his http://www.wowhead.com/spell=207313/sludge-belcher Pet is casting http://www.wowhead.com/spell=212469/hook on a Trainingsdummy, which results in the dummy is immune against the grip and the pet is jumping to the dummy. The Sludge Belcher Pet will start jumping and will fall after jumping and will follow the Deathknight again.

Expected behaviour:

The Pet should finish his uninterruptable movement and after he isn't in combat or isn't in "Stay State" he should follow his master again.

Steps to reproduce the problem:

1. Create a Unholy DK
2. Skill Sludge Belcher Talent
3. Let the Sludge Belcher cast his hook spell on a dummy
4. See the result

Branch(es): master

TC rev. hash/commit: 170d10b8a92ccbe2349ed1950a3312f477cffceb

Operating system: Windows 10

No file or test is named. Reproduce the issue with the Unholy Death Knight, Sludge Belcher, Hook, and a training dummy, then trace the PetAI movement and follow behavior. Done means the pet completes the uninterruptible movement before following its master when it is neither in combat nor in Stay state.