Correct the error msg for 'repeat' function
Correct the error msg for 'repeat' function

Now we support the map and list valuse of
the "for_each" argument to 'repeat' function,
but the error message tells "...must be lists",
it's inappropriate.

Closes-Bug: #1672936
Change-Id: I3bbe370772be7d01e63c1e88afffbd507ff75507

openstack/heat,noironetworks/heat,openstack/heat,noironetworks/heat