Fix compilation error in clang

8 jobs for master
Status Job ID Name Coverage
  Test
failed #875
amd64
job_clang_amd64

03:55:32

failed #879
amd64
job_clang_amd64_nosh

04:20:48

failed #877
amd64
job_clang_py2_amd64

03:55:33

failed #872
i386
job_gcc_386

04:45:31

failed #874
amd64
job_gcc_amd64

03:20:31

failed #878
amd64
job_gcc_amd64_nosh

03:21:22

failed #873
i386
job_gcc_py2_386

04:40:45

failed #876
amd64
job_gcc_py2_amd64

03:15:38

 
Name Stage Failure
failed
job_clang_amd64_nosh Test There is an unknown failure, please try again
  warnings.warn("tight_layout : falling back to Agg renderer")
/usr/lib/python3.5/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/python3.5/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/python3.5/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 with: exit status 1
failed
job_gcc_amd64_nosh Test There is an unknown failure, please try again
  warnings.warn("tight_layout : falling back to Agg renderer")
/usr/lib/python3.5/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/python3.5/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/python3.5/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 with: exit status 1
failed
job_clang_py2_amd64 Test There is an unknown failure, please try again
Doctest summary
===============
941 tests
3 failures in tests
0 failures in setup code
0 failures in cleanup code
build finished with problems, 137 warnings.

ERROR: Build failed with: exit status 1
failed
job_gcc_py2_amd64 Test There is an unknown failure, please try again
Doctest summary
===============
941 tests
3 failures in tests
0 failures in setup code
0 failures in cleanup code
build finished with problems, 137 warnings.

ERROR: Build failed with: exit status 1
failed
job_clang_amd64 Test There is an unknown failure, please try again
  warnings.warn("tight_layout : falling back to Agg renderer")
/usr/lib/python3.5/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/python3.5/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/python3.5/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 with: exit status 1
failed
job_gcc_386 Test There is an unknown failure, please try again
  warnings.warn("tight_layout : falling back to Agg renderer")
/usr/lib/python3/dist-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/dist-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/dist-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 with: exit status 1
failed
job_gcc_py2_386 Test There is an unknown failure, please try again
Doctest summary
===============
860 tests
4 failures in tests
0 failures in setup code
0 failures in cleanup code
build finished with problems, 137 warnings.

ERROR: Build failed with: exit status 1
failed
job_gcc_amd64 Test There is an unknown failure, please try again
  warnings.warn("tight_layout : falling back to Agg renderer")
/usr/lib/python3.5/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/python3.5/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/python3.5/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 with: exit status 1