title: git-gui command crashes on macOS Sierra
body: <p>After update to macOS Sierra, <code>git-gui</code> command crashes with an error:</p>
  
  <pre>
  Wish[23862:202062] *** Terminating app due to uncaught exception 'CALayerInvalidGeometry', reason: 'CALayer position contains NaN: [0 nan]'
  *** First throw call stack:
  (
      0   CoreFoundation                      0x00007fff8cd9252b __exceptionPreprocess + 171
      1   libobjc.A.dylib                     0x00007fffa146acad objc_exception_throw + 48
      2   CoreFoundation                      0x00007fff8ce10a0d +[NSException raise:format:] + 205
      3   QuartzCore                          0x00007fff92938980 _ZN2CA5Layer12set_positionERKNS_4Vec2IdEEb + 152
      4   QuartzCore                          0x00007fff92938af5 -[CALayer setPosition:] + 44
      5   QuartzCore                          0x00007fff9293914b -[CALayer setFrame:] + 644
      6   CoreUI                              0x00007fff986e2112 _ZN20CUICoreThemeRenderer26MakeOrUpdateScrollBarLayerEPK13CUIDescriptoraPP7CALayer + 1284
      7   CoreUI                              0x00007fff986de317 _ZN20CUICoreThemeRenderer19CreateOrUpdateLayerEPK13CUIDescriptorPP7CALayer + 1755
      8   CoreUI                              0x00007fff986604d1 _ZN11CUIRenderer19CreateOrUpdateLayerEPK14__CFDictionaryPP7CALayer + 175
      9   CoreUI                              0x00007fff98663185 CUICreateOrUpdateLayer + 221
      10  AppKit                              0x00007fff8b3c7623 -[NSCompositeAppearance _callCoreUIWithBlock:options:] + 226
      11  AppKit                              0x00007fff8aa74a9d -[NSAppearance _createOrUpdateLayer:options:] + 76
      12  AppKit                              0x00007fff8aced143 -[NSScrollerImp _animateToRolloverState] + 274
      13  AppKit                              0x00007fff8acacb79 __49-[NSScrollerImp _installDelayedRolloverAnimation]_block_invoke + 673
      14  AppKit                              0x00007fff8ab73331 -[NSScrollerImp _doWork:] + 15
      15  Foundation                          0x00007fff8e770c88 __NSFireDelayedPerform + 417
      16  CoreFoundation                      0x00007fff8cd11e14 __CFRUNLOOP_IS_CALLING_OUT_TO_A_TIMER_CALLBACK_FUNCTION__ + 20
      17  CoreFoundation                      0x00007fff8cd11a9f __CFRunLoopDoTimer + 1071
      18  CoreFoundation                      0x00007fff8cd115fa __CFRunLoopDoTimers + 298
      19  CoreFoundation                      0x00007fff8cd09021 __CFRunLoopRun + 2065
      20  CoreFoundation                      0x00007fff8cd085b4 CFRunLoopRunSpecific + 420
      21  Tcl                                 0x0000000101834b43 Tcl_WaitForEvent + 314
      22  Tcl                                 0x00000001018045cd Tcl_DoOneEvent + 274
      23  Tk                                  0x0000000101672f4f Tk_MainLoop + 33
      24  Tk                                  0x000000010167ea5b Tk_MainEx + 1566
      25  Wish                                0x0000000101658542 Wish + 9538
      26  libdyld.dylib                       0x00007fffa1d48255 start + 1
  )
  libc++abi.dylib: terminating with uncaught exception of type NSException
  error: git-gui died of signal 6
  </pre>
  
  <p>Does anybody have the same problem and a solution for this?</p>