RussWhitehead/HPCC-Platform — comment on commit 0ce6e9e391e33883320605bd1df36505bea1bfb3
File: system/jlib/jtime.cpp line 899
By ghalliday:

I think this should probably say
idx -= (last+1-first);
otherwise a month range of dec-jan will add months 12,0,1 instead of 12,1. Whether that causes any subsequent problems I don't know.