fix for readthedocs build failure

setup.py

@@ -134,6 +134,13 @@ def version():
     "Topic :: Scientific/Engineering :: Bio-Informatics",
 ]
 
+# Additional check to bypass scikit-learn dependency 
+# issues addressed in scikit-learn/scikit-learn#4164
+on_rtd = os.environ.get('READTHEDOCS') == 'True'
+if on_rtd:
+    SETUPREQUIREMENTS = ['numpy', 'scipy']
+else:
+    SETUPREQUIREMENTS = []
 
 # Do the actual setup below
 setup(
@@ -150,6 +157,7 @@ def version():
     url=URL,
     packages=PACKAGES,
     package_dir={PACKAGE_NAME: PACKAGE_DIR},
+    setup_requires=SETUPREQUIREMENTS,
     install_requires=DEPENDENCIES,
     scripts=SCRIPTS,
     platforms=PLATFORMS,