scikit-learn with shared CBLAS and BLAS

If you have your own copies of BLAS and CBLAS installed as shared libraries, the default build of scikit-learn may end up not finding libblas.so which libcblas.so depends on.

You may, when doing "from sklearn import svm",  get an error like:

from . import libsvm, liblinearImportError: /usr/local/blas/lib64/libcblas.so: undefined symbol: cgemv_

To fix it, modify the private _build_utils module:

scikit-learn-0.xx/sklearn/_build_utils/__init__.py

--- __init__.py.orig    2016-11-08 16:19:49.920389034 -0500
+++ __init__.py 2016-11-08 15:58:42.456085829 -0500
@@ -27,7 +27,7 @@

     blas_info = get_info('blas_opt', 0)
     if (not blas_info) or atlas_not_found(blas_info):
-        cblas_libs = ['cblas']
+        cblas_libs = ['cblas', 'blas']
         blas_info.pop('libraries', None)
     else:
         cblas_libs = blas_info.pop('libraries', [])