pylab导入后，ipython调试器充满了Qt错误

导入任何与pyqt相关的内容后，我无法在ipython中使用调试器。

如果我不导入任何内容并调试一个错误的验尸报告，例如

$ ipython3

In [1]: abc
---------------------------------------------------------------------------
NameError                                 Traceback (most recent call last)
<ipython-input-1-03cfd743661f> in <module>
----> 1 abc

NameError: name 'abc' is not defined

In [2]: %debug
> <ipython-input-1-03cfd743661f>(1)<module>()
----> 1 abc

ipdb> 

一切都很好，但是如果我用pyqt5后端启动ipython3，我会得到

$ ipython3 --pylab=qt5

In [1]: abc
---------------------------------------------------------------------------
NameError                                 Traceback (most recent call last)
<ipython-input-1-03cfd743661f> in <module>
----> 1 abc

NameError: name 'abc' is not defined

In [2]: %debug
> <ipython-input-1-03cfd743661f>(1)<module>()
----> 1 abc

ipdb> QObject: Cannot create children for a parent that is in a different thread.
(Parent is QApplication(0x2105860), parent's thread is QThread(0x1ccc6c0), current thread is QThread(0x7fe7940021f0)
QObject: Cannot create children for a parent that is in a different thread.
(Parent is QApplication(0x2105860), parent's thread is QThread(0x1ccc6c0), current thread is QThread(0x7fe7940021f0)
QObject: Cannot create children for a parent that is in a different thread.
(Parent is QApplication(0x2105860), parent's thread is QThread(0x1ccc6c0), current thread is QThread(0x7fe7940021f0)
QObject: Cannot create children for a parent that is in a different thread.
[...]

我没有使用qt进行开发，我仅将其用作matplotlib的后端。我知道这个问题很模糊，但是我不知道在哪里寻找解决方案。

我使用的是Ubuntu 18.04，Python 3.6.9，ipython 7.14.0，pyqt5 5.14.2。