fix #8178 conda pip interop assertion error

conda/common/pkg_formats/python.py

@@ -113,7 +113,8 @@ def _check_files(self):
         for fname in self.MANDATORY_FILES:
             if self._metadata_dir_full_path:
                 fpath = join(self._metadata_dir_full_path, fname)
-                assert isfile(fpath)
+                if not isfile(fpath):
+                    raise OSError(ENOENT, strerror(ENOENT), fpath)
 
     def _check_path_data(self, path, checksum, size):
         """Normalizes record data content and format."""

conda/core/prefix_data.py

@@ -256,7 +256,8 @@ def _load_site_packages(self):
         for af in non_conda_anchor_files:
             try:
                 python_record = read_python_record(self.prefix_path, af, python_pkg_record.version)
-            except EnvironmentError:
+            except EnvironmentError as e:
+                log.info("Python record ignored for anchor path '%s'\n  due to %s", af, e)
                 continue
             except ValidationError:
                 import sys

tests/common/pkg_formats/test_python.py

@@ -5,6 +5,7 @@
 from __future__ import absolute_import, division, print_function, unicode_literals
 
 from datetime import datetime
+from errno import ENOENT
 import os
 from os.path import basename, lexists
 from pprint import pprint
@@ -523,8 +524,10 @@ def test_pydist_check_files():
 
     # Test mandatory file not found
     os.remove(fpaths[0])
-    with pytest.raises(AssertionError):
+    with pytest.raises(EnvironmentError) as exc:
         PythonInstalledDistribution(temp_path, "2.7", None)
+    assert exc.value.errno == ENOENT
+    assert temp_path in str(exc.value)
 
 
 def test_python_dist_info():