pandas: fix check with the current pytest

pandas 0.23.0 has fixed this too, but it introduces new test failures.

pkgs/development/python-modules/pandas/default.nix

@@ -55,6 +55,8 @@ in buildPythonPackage rec {
     xlwt
   ];
 
+  patches = [ ./pandas-0.22.0-pytest-3.5.1.patch ];
+
   # For OSX, we need to add a dependency on libcxx, which provides
   # `complex.h` and other libraries that pandas depends on to build.
   postPatch = optionalString isDarwin ''

pkgs/development/python-modules/pandas/pandas-0.22.0-pytest-3.5.1.patch

@@ -0,0 +1,13 @@
+--- a/pandas/tests/io/test_pytables.py
++++ b/pandas/tests/io/test_pytables.py
+@@ -5028,8 +5028,8 @@ class TestHDFStore(Base):
+             with ensure_clean_path(self.path) as path:
+                 with catch_warnings(record=True):
+                     with pytest.raises(
+-                        ValueError, msg=("cannot have non-object label "
+-                                         "DataIndexableCol")):
++                        ValueError, message=("cannot have non-object label "
++                                             "DataIndexableCol")):
+                         df.to_hdf(path, 'df', format='table',
+                                   data_columns=True)
+