AssertionError merging woff #1408
Description
Test data: https://github.com/dimaqq/kanji-sudoku/tree/gh-pages/fnt (it's my repo, a 3rd party Kanji stroke order font split into subsets)
pyftmerge stroke0.woff OK
pyftmerge stroke0.woff stroke1.woff fails with:
Traceback (most recent call last):
File "/usr/local/bin/pyftmerge", line 11, in <module>
sys.exit(main())
File "/usr/local/lib/python2.7/site-packages/fontTools/misc/loggingTools.py", line 375, in wrapper
return func(*args, **kwds)
File "/usr/local/lib/python2.7/site-packages/fontTools/merge.py", line 1122, in main
font = merger.merge(args)
File "/usr/local/lib/python2.7/site-packages/fontTools/merge.py", line 962, in merge
table = clazz(tag).merge(self, tables)
File "/usr/local/lib/python2.7/site-packages/fontTools/merge.py", line 653, in merge
DefaultTable.merge(self, m, tables)
File "/usr/local/lib/python2.7/site-packages/fontTools/merge.py", line 160, in merge
return m.mergeObjects(self, self.mergeMap, tables)
File "/usr/local/lib/python2.7/site-packages/fontTools/merge.py", line 1008, in mergeObjects
value = mergeLogic(getattr(table, key, NotImplemented) for table in tables)
File "/usr/local/lib/python2.7/site-packages/fontTools/merge.py", line 122, in mergeObjects
value = mergeLogic(getattr(table, key, NotImplemented) for table in lst)
File "/usr/local/lib/python2.7/site-packages/fontTools/merge.py", line 122, in mergeObjects
value = mergeLogic(getattr(table, key, NotImplemented) for table in lst)
File "/usr/local/lib/python2.7/site-packages/fontTools/merge.py", line 516, in mergeScriptRecords
rec.Script = mergeScripts(d[tag])
File "/usr/local/lib/python2.7/site-packages/fontTools/merge.py", line 501, in mergeScripts
self.DefaultLangSys = mergeLangSyses([s.DefaultLangSys for s in lst if s.DefaultLangSys])
File "/usr/local/lib/python2.7/site-packages/fontTools/merge.py", line 468, in mergeLangSyses
assert lst
AssertionError