fix coverage

Author: alimanfoo

numcodecs/tests/test_lzma.py

@@ -8,7 +8,7 @@
 
 try:
     from numcodecs.lzma import LZMA, _lzma
-except ImportError:
+except ImportError:  # pragma: no cover
     raise nose.SkipTest("LZMA not available")
 
 from numcodecs.tests.common import check_encode_decode, check_config, check_repr

numcodecs/tests/test_msgpacks.py

@@ -7,7 +7,7 @@
 
 try:
     from numcodecs.msgpacks import MsgPack
-except ImportError:
+except ImportError:  # pragma: no cover
     raise nose.SkipTest("msgpack-python not available")
 
 from numcodecs.tests.common import check_config, check_repr, check_encode_decode_objects