Before the patch hit, I could easily cast cobra shot back-to-back with no trouble.
Then the patch hit and now I often end up not casting it the 2nd time.
Usually, while cobra shot is 'channelling', you can use another ability when it's almost done. That ability will then be cast instantly after Cobra Shot is done. That still does work with abilities, such as Explosive and Arcane Shot. Using Cobra shot, will however only work if it is cast just before the initial Cobra Shot is done.
Here is a picture that may help illustrating my point. Has anyone else noticed this, or is it just me?
Update:
I experienced the same thing on my Mage just now. So it seems like it happens to all abilities with a cast time. And here's where it gets strange.
It only happens if I cast the same ability back-to-back.
If I however alternate with Frostbolt and Frostfire Bolt, it works just like before the patch.