BF: be resilient to optional module non-ImportError exceptions upon import

ATM h5py is giving a grief while trying to work on a filesystem without
utf-8 encoding support in filenames.

Author: yarikoptic

nibabel/optpkg.py

@@ -94,9 +94,14 @@ def optional_package(name, trip_msg=None, min_version=None):
     # fromlist=[''] results in submodule being returned, rather than the top
     # level module.  See help(__import__)
     fromlist = [''] if '.' in name else []
+    exc = None
     try:
         pkg = __import__(name, fromlist=fromlist)
-    except ImportError:
+    except ImportError as exc:
+        pass
+    except Exception as exc:  # it failed to import for some other reason
+        # e.g. h5py might have been checking file system to support UTF-8
+        # etc.  We should not blow if they blow
         pass
     else:  # import worked
         # top level module
@@ -111,8 +116,8 @@ def optional_package(name, trip_msg=None, min_version=None):
                             (name, min_version))
     if trip_msg is None:
         trip_msg = ('We need package %s for these functions, but '
-                    '``import %s`` raised an ImportError'
-                    % (name, name))
+                    '``import %s`` raised %s'
+                    % (name, name, exc))
     pkg = TripWire(trip_msg)
 
     def setup_module():

nibabel/tests/test_optpkg.py

@@ -1,6 +1,7 @@
 """ Testing optpkg module
 """
 
+import mock
 import types
 import sys
 from distutils.version import LooseVersion
@@ -36,6 +37,12 @@ def test_basic():
     assert_good('os.path')
     # We never have package _not_a_package
     assert_bad('_not_a_package')
+    def raise_Exception(*args, **kwargs):
+        raise Exception(
+            "non ImportError could be thrown by some malfunctioning module "
+            "upon import, and optional_package should catch it too")
+    with mock.patch('__builtin__.__import__', side_effect=raise_Exception):
+        assert_bad('nottriedbefore')
 
 
 def test_versions():