Why is an MD5 hash created by Python different from one created using echo and md5sum in the shell?

A Python MD5 hash is different than the one created by the md5sum command on the shell. Why?

>>> import hashlib
>>> h = hashlib.md5()
>>> h.update("mystringforhash")
>>> print h.hexdigest()
86b6423cb6d211734fc7d81bbc5e11d3 # Result from Python


$ echo mystringforhash | md5sum
686687dd68c5de717b34569dbfb8d3c3  - # Result on the shell