Delay import from matplotlib_inline.backend_inline (#14330)...
Delay import from matplotlib_inline.backend_inline (#14330)
Possible fix for
#14329.
With this change, the reproducers from the issue become:
```python
$ ipython
<snip>
In [1]: import matplotlib.pyplot as plt; plt.set_loglevel("debug")
In [2]: %matplotlib tk
DEBUG:matplotlib.pyplot:Loaded backend TkAgg version 8.6.
```
It is still possible to call `matplotlib.pyplot.switch_backend` twice
but only if you request `%matplotlib inline`, and the `switch_backend`
is called with same correct backend twice. This isn't ideal but it
doesn't cause any problems apart from being a little slower than
necessary.
