Bug#900777: fontmake: fails to rebuild fonts-firacode from its glyphs source

[Fabian Greffrath <fabian@debian.org>]

Package: fontmake
Version: 1.4.0-2
Severity: normal

Hi fontmake mates,

the following happens when I try to rebuild fonts-firacode from its
glyphs source. I have absolutely no clue what that means. Could you
probably have a look, please?

$ fontmake -g FiraCode.glyphs 
INFO:fontmake.font_project:Building master UFOs and designspace from Glyphs source
INFO:glyphsLib.parser:Parsing .glyphs file
INFO:glyphsLib:Loading to UFOs
INFO:glyphsLib.util:Writing master_ufo/FiraCode-Regular.ufo
INFO:glyphsLib.util:Writing master_ufo/FiraCode-Bold.ufo
INFO:fontmake.font_project:Building OTFs
INFO:fontmake.font_project:Decomposing glyphs for FiraCode-Regular
INFO:fontmake.font_project:Decomposing glyphs for FiraCode-Bold
INFO:fontmake.font_project:Removing overlaps for FiraCode-Regular
INFO:fontmake.font_project:Removing overlaps for FiraCode-Bold
INFO:fontmake.font_project:Saving OTF for FiraCode-Regular
WARNING:ufo2ft.outlineCompiler:The copyright was normalized for storage in the CFF table and consequently some characters were dropped: 'Copyright Copyright 2015 by Nikita Prokopov'
Traceback (most recent call last):
  File "/usr/bin/fontmake", line 11, in <module>
    load_entry_point('fontmake==1.4.0', 'console_scripts', 'fontmake')()
  File "/usr/lib/python3/dist-packages/fontmake/__main__.py", line 186, in main
    project.run_from_glyphs(glyphs_path, **args)
  File "/usr/lib/python3/dist-packages/fontmake/font_project.py", line 369, in run_from_glyphs
    designspace_path, instance_data=instance_data, **kwargs)
  File "/usr/lib/python3/dist-packages/fontmake/font_project.py", line 437, in run_from_designspace
    interpolate_layout_from=interpolate_layout_from, **kwargs)
  File "/usr/lib/python3/dist-packages/fontmake/font_project.py", line 476, in run_from_ufos
    ufos, remove_overlaps, **kwargs)
  File "/usr/lib/python3/dist-packages/fontmake/font_project.py", line 169, in build_otfs
    self.save_otfs(ufos, **kwargs)
  File "/usr/lib/python3/dist-packages/fontTools/misc/loggingTools.py", line 372, in wrapper
    return func(*args, **kwds)
  File "/usr/lib/python3/dist-packages/fontmake/font_project.py", line 286, in save_otfs
    font = compileOTF(ufo, optimizeCFF=subroutinize, **compiler_options)
  File "/usr/lib/python3/dist-packages/ufo2ft/__init__.py", line 69, in compileOTF
    featureCompiler.compile()
  File "/usr/lib/python3/dist-packages/ufo2ft/featureCompiler.py", line 56, in compile
    self.setupFile_featureTables()
  File "/usr/lib/python3/dist-packages/ufo2ft/featureCompiler.py", line 143, in setupFile_featureTables
    filename=feapath)
  File "/usr/lib/python3/dist-packages/fontTools/feaLib/builder.py", line 25, in addOpenTypeFeaturesFromString
    addOpenTypeFeatures(font, featurefile)
  File "/usr/lib/python3/dist-packages/fontTools/feaLib/builder.py", line 16, in addOpenTypeFeatures
    builder.build()
  File "/usr/lib/python3/dist-packages/fontTools/feaLib/builder.py", line 87, in build
    table = self.makeTable(tag)
  File "/usr/lib/python3/dist-packages/fontTools/feaLib/builder.py", line 468, in makeTable
    table.LookupList.Lookup = self.buildLookups_(tag)
  File "/usr/lib/python3/dist-packages/fontTools/feaLib/builder.py", line 458, in buildLookups_
    return [l.build() for l in lookups]
  File "/usr/lib/python3/dist-packages/fontTools/feaLib/builder.py", line 458, in <listcomp>
    return [l.build() for l in lookups]
  File "/usr/lib/python3/dist-packages/fontTools/feaLib/builder.py", line 1168, in build
    self.setBacktrackCoverage_(prefix, st)
  File "/usr/lib/python3/dist-packages/fontTools/feaLib/builder.py", line 1088, in setBacktrackCoverage_
    coverage = otl.buildCoverage(p, self.glyphMap)
  File "/usr/lib/python3/dist-packages/fontTools/otlLib/builder.py", line 11, in buildCoverage
    self.glyphs = sorted(glyphs, key=glyphMap.__getitem__)
KeyError: ''

Thanks!

Cheers,
 - Fabian

-- System Information:
Debian Release: buster/sid
  APT prefers testing
  APT policy: (990, 'testing'), (500, 'unstable-debug'), (500, 'experimental'), (500, 'unstable')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 4.15.0-3-amd64 (SMP w/4 CPU cores)
Locale: LANG=de_DE.UTF-8, LC_CTYPE=de_DE.UTF-8 (charmap=UTF-8), LANGUAGE=de_DE.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages fontmake depends on:
ii  python3           3.6.5-3
ii  python3-fontmake  1.4.0-2

fontmake recommends no packages.

fontmake suggests no packages.

-- no debconf information