QKeySequence differences between PySide and PySide2

As I'm currently porting a gui application from Python 2.7.14/PySide 1.2.4 to Python 3.7.1/PySide2 5.11.2 I'm encountering a few problems with the shortcut machinery. More specifically:

• QKeySequence instantiation seems to return different/surprising results in PySide2 compared to PySide.
• The + operators on Qt.Key_* enums don't seem to return the expected results. For example QKeySequence(Qt.SHIFT + Qt.CTRL + Qt.Key_Z) doesn't seem to work properly.
• When using string codes for instantiation of QKeySequences it works, for example QKeySequence("Shift+Ctrl+Z") seems functional.
• Instantiation with QKeySequence.StandardKey like QKeySequence(QKeySequence.Redo) simply crashes in PySide2.

Are these known bugs? Did something change in the expected usage? Did I miss something in the docs?

Win7x64/Python 3.7.1/PySide2 5.11.2 (disfunctional/crashing)

# -*- coding: utf-8 -*-
"""Test QKeySequence equality/matching in PySide2."""
from PySide2.QtCore import Qt
from PySide2.QtGui import QKeySequence

sequence_a = QKeySequence("Shift+Ctrl+Z")
sequence_b = QKeySequence(Qt.SHIFT + Qt.CTRL + Qt.Key_Z)

# string representation
print(sequence_a.toString())
print(sequence_b.toString())

print("-"*20)

# equality/matching
print(sequence_a.matches(sequence_b))
print(sequence_a == sequence_b)

print("-"*20)

# this causes a crash in PySide2 (Process finished with exit code -1073741819 (0xC0000005))
print(QKeySequence(QKeySequence.Redo))

# Ctrl+Shift+Z
# [
# --------------------
# PySide2.QtGui.QKeySequence.SequenceMatch.NoMatch
# False
# --------------------
# Process finished with exit code -1073741819 (0xC0000005)

Win7x64/Python 2.7.14/PySide 1.2.4 (working)

# -*- coding: utf-8 -*-
"""Test QKeySequence equality/matching in PySide."""
from PySide.QtCore import Qt
from PySide.QtGui import QKeySequence

sequence_a = QKeySequence("Shift+Ctrl+Z")
sequence_b = QKeySequence(Qt.SHIFT + Qt.CTRL + Qt.Key_Z)

# string representation
print(sequence_a.toString())
print(sequence_b.toString())

print("-"*20)

# equality/matching
print(sequence_a.matches(sequence_b))
print(sequence_a == sequence_b)

print("-"*20)

# this works in PySide
print(QKeySequence(QKeySequence.Redo))

# Ctrl+Shift+Z
# Ctrl+Shift+Z
# --------------------
# PySide.QtGui.QKeySequence.SequenceMatch.ExactMatch
# True
# --------------------
# PySide.QtGui.QKeySequence(67108953, 0, 0, 0)

As for now, two possible workarounds have emerged:

• Error: QKeySequence(Qt.SHIFT + Qt.CTRL + Qt.Key_Z).toString() --> "["
• Fix with enforced precedence: QKeySequence(Qt.SHIFT + (Qt.CTRL + Qt.Key_Z)).toString() --> "Ctrl+Shift+Z"
• Fix with bitwise or operator: QKeySequence(Qt.ShiftModifier | Qt.CTRL | Qt.Key_Z).toString() --> "Ctrl+Shift+Z"

While they seem to solve the direct problem at hand, I don't find them to be all that great for various reasons. The general issue may still possibly qualify as PySide2 bug!?