laplacian(): Remove innocuous warning

6 jobs for master in 310 minutes and 40 seconds (queued for 2 seconds)
Status Name Job ID Coverage
  Test
passed job_clang_amd64 #2126
amd64

05:10:40

failed job_clang_amd64_nosh #2130
amd64

05:08:10

passed job_clang_py2_amd64 #2128
amd64

05:08:36

passed job_gcc_amd64 #2125
amd64

03:57:03

failed job_gcc_amd64_nosh #2129
amd64

03:55:50

passed job_gcc_py2_amd64 #2127
amd64

03:54:54

 
Name Stage Failure
failed
job_gcc_amd64_nosh Test There is an unknown failure, please try again
  max_open_warning, RuntimeWarning)
<string>:10: VisibleDeprecationWarning: using a non-integer number instead of an integer will result in an error in the future
/usr/lib/python3.6/site-packages/matplotlib/pyplot.py:524: RuntimeWarning: More than 20 figures have been opened. Figures created through the pyplot interface (`matplotlib.pyplot.figure`) are retained until explicitly closed and may consume too much memory. (To control this warning, see the rcParam `figure.max_open_warning`).
max_open_warning, RuntimeWarning)
/usr/lib/python3.6/site-packages/matplotlib/pyplot.py:524: RuntimeWarning: More than 20 figures have been opened. Figures created through the pyplot interface (`matplotlib.pyplot.figure`) are retained until explicitly closed and may consume too much memory. (To control this warning, see the rcParam `figure.max_open_warning`).
max_open_warning, RuntimeWarning)
/usr/lib/python3.6/site-packages/matplotlib/pyplot.py:524: RuntimeWarning: More than 20 figures have been opened. Figures created through the pyplot interface (`matplotlib.pyplot.figure`) are retained until explicitly closed and may consume too much memory. (To control this warning, see the rcParam `figure.max_open_warning`).
max_open_warning, RuntimeWarning)
ERROR: Build failed: exit status 1
failed
job_clang_amd64_nosh Test There is an unknown failure, please try again
    0 failures in cleanup code
build finished with problems, 157 warnings.
/usr/lib/python3.6/site-packages/matplotlib/tight_layout.py:222: UserWarning: tight_layout : falling back to Agg renderer
warnings.warn("tight_layout : falling back to Agg renderer")
/usr/lib/python3.6/site-packages/matplotlib/pyplot.py:524: RuntimeWarning: More than 20 figures have been opened. Figures created through the pyplot interface (`matplotlib.pyplot.figure`) are retained until explicitly closed and may consume too much memory. (To control this warning, see the rcParam `figure.max_open_warning`).
max_open_warning, RuntimeWarning)
/usr/lib/python3.6/site-packages/matplotlib/tight_layout.py:222: UserWarning: tight_layout : falling back to Agg renderer
warnings.warn("tight_layout : falling back to Agg renderer")
ERROR: Build failed: exit status 1