phatch 0.27 watermarks crash

[ildar r. khasanshin]

the file is selected, the watermark is displayed in the console error:

Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/wx-3.0-gtk2/wx/_core.py", line 16765, in <lambda>
    lambda event: event.callable(*event.args, **event.kw) )
  File "/usr/share/phatch/phatch/lib/pyWx/popup.py", line 364, in OnChange
    icon_size=self.icon_size,
  File "/usr/share/phatch/phatch/lib/pyWx/imageFileBrowser.py", line 102, in __init__
    self.image_list = ListCtrl(self.panel, files, icon_size)
  File "/usr/share/phatch/phatch/lib/pyWx/imageFileBrowser.py", line 54, in __init__
    pil_wxBitmap(open_thumb(file, size=icon_size)))
  File "/usr/lib/python2.7/dist-packages/wx-3.0-gtk2/wx/_gdi.py", line 6735, in Add
    return _gdi_.ImageList_Add(*args, **kwargs)
wx._core.PyAssertionError: C++ assertion "(bitmap.GetWidth() >= m_width && bitmap.GetHeight() == m_height) || (m_width == 0 && m_height == 0)" failed at ../src/generic/imaglist.cpp(66) in Add(): invalid bitmap size in wxImageList: this might work on this platform but definitely won't under Windows.

phatch 0.2.7
ubuntu 16.10 x64 unity