Fix RuntimeError/Issue #67

[Corey-J-Bukolt]

It seems this is caused by line 551 and the fact that in Python3 .items() creates an iterator object unlike Py2 which creates a copy of the object. Using dict(ri_rel).items() creates an iterator of a copy of ri_rel allowing 551 to modify the original ri_rel without triggering an exception.

Tested on my own system without issues.

[srl295]

Fixes: #67