Fix issue with empty cow_whitelist (#59946)

* Fix issue with empty cow_whitelist. Fixes #45631

* Account for None

changelogs/fragments/45631-empty-cow-whitelist.yml

@@ -0,0 +1,2 @@
+bugfixes:
+- cowsay - Fix issue with an empty cow_whitelist (https://github.com/ansible/ansible/issues/45631)

lib/ansible/utils/display.py

@@ -110,7 +110,7 @@ class Display(with_metaclass(Singleton, object)):
                 cmd = subprocess.Popen([self.b_cowsay, "-l"], stdout=subprocess.PIPE, stderr=subprocess.PIPE)
                 (out, err) = cmd.communicate()
                 self.cows_available = set([to_text(c) for c in out.split()])
-                if C.ANSIBLE_COW_WHITELIST:
+                if C.ANSIBLE_COW_WHITELIST and any(C.ANSIBLE_COW_WHITELIST):
                     self.cows_available = set(C.ANSIBLE_COW_WHITELIST).intersection(self.cows_available)
             except Exception:
                 # could not execute cowsay for some reason