forg fails to load an image

[Traumschule Riebau]

OS: Ubuntu artful

$ forg gopher://parazyd.cf/I/pub/tmp/screenshots/screenshot0050.png
===> Uncaching
"/home/user/.forg/cache/parazyd.cf/I/pub/tmp/screenshots/screenshot0050.png"
Exception in Tkinter callback Traceback (most recent call last):
  File "/usr/lib/python2.7/lib-tk/Tkinter.py", line 1544, in __call__
    return self.func(*args)
  File "/usr/share/forg/TkGui.py", line 456, in go
    self.goElsewhere(res)
  File "/usr/share/forg/TkGui.py", line 459, in goElsewhere
    self.CONTENT_BOX.goElsewhere(resource, usecache, args)
  File "/usr/share/forg/forg.py", line 349, in goElsewhere
    self.createResponseWidget()
  File "/usr/share/forg/forg.py", line 444, in createResponseWidget
    filename=cfilename)
  File "/usr/share/forg/GUISaveFile.py", line 89, in __init__
    self.packSaveContent()
  File "/usr/share/forg/GUISaveFile.py", line 176, in packSaveContent
    default_filename = re.sub(strtofind, char, default_filename)
  File "/usr/lib/python2.7/re.py", line 155, in sub
    return _compile(pattern, flags).sub(repl, string, count)
  File "/usr/lib/python2.7/re.py", line 286, in _subx
    template = _compile_repl(template, pattern)
  File "/usr/lib/python2.7/re.py", line 273, in _compile_repl
    raise error, v # invalid expression
error: bogus escape (end of line)

ii forg 0.5.1-7.2 all Graphical Gopher Browser
ii python 2.7.14-2ubuntu1 i386 interactive high-level object-oriented language (
un python-central <none> <none> (no description available)
un python-imaging-tk <none> <none> (no description available)
ii python-pmw 1.3.2-6build1 all Pmw -- Python MegaWidgets
ii python-tk 2.7.14-1 i386 Tkinter - Writing Tk applications with Python