failure to break blocks

This error the version 14w27b. Describe what you think should happen here:
break the selected blocks

• What really happened was: the blocks back or side broke
  Describe what happened here:
  when I was playing survival on latest version, when some block broke sometimes broke the back or side of

• Steps to reproduce: *
  1. Put a step by step guide on how to activate the error here
  2 .... Nose
  3 .... Nose