Steps to reproduce:
1. Download and open attached project "CrossfadeTest.zip"
2. Open and play scene "crossfade"
3. Note the four buttons

Actual result: (Pressing buttons under "CrossFade") Press Walk, and before animation has finished transitioning press Run (or vice versa). Notice that animation doesn't change unless it has finished transitioning
Expected result: Animation's transition can be interrupted, just like in CrossFadeInFixedTime

Note: If the result is not seen clearly enough, increase transition time within CrossFadeTest.cs script

Tested and reproduced on:
Windows 10
Unity 5.2.4p1, 5.3.5p1, 5.4.0b19