fix error messages closes pandas-dev#18089

Author: jbrockmendel

pandas/__init__.py

@@ -28,7 +28,11 @@
                              tslib as _tslib)
 except ImportError as e:  # pragma: no cover
     # hack but overkill to use re
-    module = str(e).replace('cannot import name ', '')
+    module = str(e).replace('cannot import name ', '')\
+                   .replace('No module named ', '')
+    if 'does not export' in module:
+        # GH#18089
+        raise
     raise ImportError("C extension: {0} not built. If you want to import "
                       "pandas from the source directory, you may need to run "
                       "'python setup.py build_ext --inplace --force' to build "