AttributeError: 'QWheelEvent' object has no attribute 'delta'

Created originally on Bitbucket by Anonymous

I got a following error while using HG workbench:

To reproduce:

1. Choose a commit,
2. Select file and choose 'View change as unified diff output'
3. Use Find (Ctrl+F), enter a regular expression
4. Use mouse wheel scroll with cursor and mouse over the search text box

 #!python
** Mercurial version (4.6).  TortoiseHg version (4.6)
** Command: 
** CWD: C:\Program Files\TortoiseHg
** Encoding: cp1252
** Extensions loaded: rebase, strip, extdiff, tortoisehg.util.configitems, purge, mq
** Python version: 2.7.13 (v2.7.13:a06454b1afa1, Dec 17 2016, 20:53:40) [MSC v.1500 64 bit (AMD64)]
** Windows version: sys.getwindowsversion(major=6, minor=2, build=9200, platform=2, service_pack='')
** Processor architecture: x64
** Qt-5.9.2 PyQt-5.9.1 QScintilla-2.10.2.dev1711012104
Traceback (most recent call last):
  File "tortoisehg\hgqt\qscilib.pyo", line 594, in wheelEvent
AttributeError: 'QWheelEvent' object has no attribute 'delta'