inputField = arcpy.ListFields(inputLayer, inputFieldName)[0] fieldType = inputField.type
I got the same result in 10.2.1--small integer instead of GUID. Is there a patch to fix this bug (or is it not worth the bother, just wait to get upgraded)?
Did you look over Esri Support 10.2 (10.2.1, 10.2.2) ? Seeing nothing on the ArcGIS 10.2.2 Issues Addressed List appears related to this issue, I suspect no patch or hotfix was issued at 10.2.1 for it.
In terms of upgrades and when it was addresses exactly, I don't know, but you could peruse the issues addressed lists for the releases since 10.2.1 to 10.5:
(I know, nice path/URL standardization on Esri's part)