Fix another corner case of too many warnings for world readable current working directory

There should be no warning if there is no ansible.cfg file i nthe
current working directory.

changelogs/fragments/more-world-readable-warning-skips.yaml

@@ -0,0 +1,7 @@
+---
+bugfixes:
+- The fix for `CVE-2018-10875 <https://access.redhat.com/security/cve/cve-2018-10875>`_
+  prints out a warning message about skipping a config file from a world
+  writable current working directory.  However, if the user is in a world
+  writable current working directory which does not contain a config file, it
+  should not print a warning message.  This release fixes that extaneous warning.

lib/ansible/config/manager.py

@@ -176,10 +176,14 @@ def find_ini_config_file(warnings=None):
     try:
         cwd = os.getcwd()
         perms = os.stat(cwd)
+        cwd_cfg = os.path.join(cwd, "ansible.cfg")
         if perms.st_mode & stat.S_IWOTH:
+            # Working directory is world writable so we'll skip it.
+            # Still have to look for a file here, though, so that we know if we have to warn
+            if os.path.exists(cwd_cfg):
                 warn_cmd_public = True
         else:
-            potential_paths.append(os.path.join(cwd, "ansible.cfg"))
+            potential_paths.append(cwd_cfg)
     except OSError:
         # If we can't access cwd, we'll simply skip it as a possible config source
         pass

test/units/config/manager/test_find_ini_config_file.py

@@ -144,6 +144,31 @@ class TestFindIniFile:
         assert find_ini_config_file(warnings) is None
         assert warnings == set()
 
+    # ANSIBLE_CONFIG not specified
+    @pytest.mark.parametrize('setup_env', [[None]], indirect=['setup_env'])
+    # All config files are present except in cwd
+    @pytest.mark.parametrize('setup_existing_files',
+                             [[('/etc/ansible/ansible.cfg', cfg_in_homedir, cfg_file, alt_cfg_file)]],
+                             indirect=['setup_existing_files'])
+    def test_no_cwd_cfg_no_warning_on_writable(self, setup_env, setup_existing_files, monkeypatch):
+        """If the cwd is writable but there is no config file there, move on with no warning"""
+        real_stat = os.stat
+
+        def _os_stat(path):
+            if path == working_dir:
+                from posix import stat_result
+                stat_info = list(real_stat(path))
+                stat_info[stat.ST_MODE] |= stat.S_IWOTH
+                return stat_result(stat_info)
+            else:
+                return real_stat(path)
+
+        monkeypatch.setattr('os.stat', _os_stat)
+
+        warnings = set()
+        assert find_ini_config_file(warnings) == cfg_in_homedir
+        assert len(warnings) == 0
+
     # ANSIBLE_CONFIG not specified
     @pytest.mark.parametrize('setup_env', [[None]], indirect=['setup_env'])
     # All config files are present