Description of problem:
Simply running Calibre on Fedora Rawhide.

Version-Release number of selected component:
calibre-2.55.0-4.fc25

Additional info:
reporter:       libreport-2.7.0
cmdline:        python2 /bin/calibre
executable:     /bin/calibre
kernel:         4.6.0-0.rc4.git3.1.fc25.x86_64
pkg_vendor:     Fedora Project
runlevel:       N 5
type:           Python
uid:            1000

Truncated backtrace:
__init__.py:977:load_calibre_style:TypeError: a dict value has type 'unicode' but 'QString' is expected

Traceback (most recent call last):
  File "/bin/calibre", line 20, in <module>
    sys.exit(calibre())
  File "/usr/lib64/calibre/calibre/gui_launch.py", line 62, in calibre
    main(args)
  File "/usr/lib64/calibre/calibre/gui2/main.py", line 495, in main
    app, opts, args = init_qt(args)
  File "/usr/lib64/calibre/calibre/gui2/main.py", line 101, in init_qt
    app = Application(args, override_program_name=override)
  File "/usr/lib64/calibre/calibre/gui2/__init__.py", line 866, in __init__
    self.load_calibre_style()
  File "/usr/lib64/calibre/calibre/gui2/__init__.py", line 977, in load_calibre_style
    self.pi.load_style(icon_map)
TypeError: a dict value has type 'unicode' but 'QString' is expected

Local variables in innermost frame:
icon_map: {43: u'/usr/share/calibre/images/save.png', 39: u'/usr/share/calibre/images/ok.png', 40: u'/usr/share/calibre/images/window-close.png', 41: u'/usr/share/calibre/images/help.png', 42: u'/usr/share/calibre/images/document_open.png', 11: u'/usr/share/calibre/images/dialog_error.png', 44: u'/usr/share/calibre/images/window-close.png', 45: u'/usr/share/calibre/images/ok.png', 12: u'/usr/share/calibre/images/dialog_question.png', 47: u'/usr/share/calibre/images/trash.png', 48: u'/usr/share/calibre/images/ok.png', 49: u'/usr/share/calibre/images/window-close.png', 9: u'/usr/share/calibre/images/dialog_information.png', 59: u'/usr/share/calibre/images/view-refresh.png', 10: u'/usr/share/calibre/images/dialog_warning.png'}
k: 'DialogNoButton'
p: u'/usr/share/calibre/images/save.png'
v: u'/usr/share/calibre/images/window-close.png'
pcache: {u'save.png': u'/usr/share/calibre/images/save.png', u'dialog_error.png': u'/usr/share/calibre/images/dialog_error.png', u'ok.png': u'/usr/share/calibre/images/ok.png', u'document_open.png': u'/usr/share/calibre/images/document_open.png', u'help.png': u'/usr/share/calibre/images/help.png', u'trash.png': u'/usr/share/calibre/images/trash.png', u'dialog_warning.png': u'/usr/share/calibre/images/dialog_warning.png', u'view-refresh.png': u'/usr/share/calibre/images/view-refresh.png', u'window-close.png': u'/usr/share/calibre/images/window-close.png', u'dialog_information.png': u'/usr/share/calibre/images/dialog_information.png', u'dialog_question.png': u'/usr/share/calibre/images/dialog_question.png'}
self: <calibre.gui2.Application object at 0x7f7d6ecbb050>