fontmake: fontmake error when compiling Roboto Italic variable fonts

After updating fontmake on Feb 6th at 10pm cst (latest commit was this), I attempted to generate new Roboto variable fonts using the interpolated source ufos found here: https://github.com/erinmclaughlin/roboto/tree/everything-in-source-interp/src/v2

I used this command fontmake -m RobotoUpright.designspace -o variable --no-production-names to generate RobotoUpright-GX.ttf successfully.

Unfortunately, fontmake -m RobotoItalic.designspace -o variable --no-production-names did not work. Here are the last few lines of output before the error, in case it is helpful:

File “/Users/erinmclaughlin/env/lib/python2.7/site-packages/fontTools/varLib/merger.py”, line 410, in merge subtables = [_Lookup_PairPos_subtables_canonicalize(l.SubTable, merger.font) for l in lst] File “/Users/erinmclaughlin/env/lib/python2.7/site-packages/fontTools/varLib/merger.py”, line 397, in _Lookup_PairPos_subtables_canonicalize tail.insert(0, _Lookup_PairPosFormat1_subtables_merge_overlay(head, font)) File “/Users/erinmclaughlin/env/lib/python2.7/site-packages/fontTools/varLib/merger.py”, line 376, in _Lookup_PairPosFormat1_subtables_merge_overlay [v.PairSet for v in lst]) File “/Users/erinmclaughlin/env/lib/python2.7/site-packages/fontTools/varLib/merger.py”, line 144, in merge_GlyphOrders assert all(sorted(vs, key=sortKey) == vs for vs in lst) AssertionError: (‘Lookup’, ‘[1]’, ‘list’, ‘.Lookup’, ‘LookupList’, ‘.LookupList’, ‘GPOS’, ‘.table’, 'table_G_P_O_S’)

The Italic variable font did successfully compile several weeks ago using the --no-gpos command before I updated fontmake.

Let me know if there’s anything else I can provide that can be of help. Thanks!