Clear Console not working on Windows

Description

What steps will reproduce the problem?

%clear The system cannot find the path specified.

Versions

• Spyder version: 4.0.0b5
• Python version: 3.7.3
• Qt version: 5.9.6
• PyQt5 version: 5.9.2
• Operating System: Windows 10

Dependencies

cloudpickle >=0.5.0          :  1.2.1 (OK)
pygments >=2.0               :  2.4.2 (OK)
qtconsole >=4.5.5            :  4.5.5 (OK)
nbconvert >=4.0              :  5.5.0 (OK)
sphinx >=0.6.6               :  2.1.2 (OK)
pylint >=0.25                :  2.3.1 (OK)
psutil >=0.3                 :  5.6.3 (OK)
qtawesome >=0.5.7            :  0.5.7 (OK)
qtpy >=1.5.0                 :  1.8.0 (OK)
pickleshare >=0.4            :  0.7.5 (OK)
zmq >=17                     :  18.0.0 (OK)
chardet >=2.0.0              :  3.0.4 (OK)
numpydoc >=0.6.0             :  0.9.1 (OK)
spyder_kernels >=1.5.0;<2.0.0:  1.5.0 (OK)
qdarkstyle >=2.7             :  2.7 (OK)
atomicwrites >=1.2.0         :  1.3.0 (OK)
diff_match_patch >=20181111  :  20181111 (OK)
watchdog                     :  None (OK)
keyring                      :  None (OK)
pexpect >=4.4.0              :  4.7.0 (OK)
pympler                      :  None (OK)
sympy >=0.7.3                :  1.4 (OK)
cython >=0.21                :  0.29.12 (OK)
IPython >=4.0                :  7.6.1 (OK)
matplotlib >=2.0.0           :  3.1.0 (OK)
pandas >=0.13.1              :  0.24.2 (OK)
numpy >=1.7                  :  1.16.4 (OK)
scipy >=0.17.0               :  1.2.1 (OK)
pyls >=0.28.2;<0.29.0        :  0.28.3 (OK)
rtree >=0.8.3                :  0.8.3 (OK)

[dalthviz]

Doing some testing, and after reading more carefully the issue in IPython (where the user specifies he is using Spyder 3.3.1), seems like the issue is actually in QtConsole and it’s not only affecting the clear magic but also other magics like ls:

Testing with IPython the clear magic cls works as expected

[ccordoba12]

This happens when your current working directory is a network mount. So avoid that until we fix it.