ipa[client,server]: Inspect validate_domain_name for 4.6 and prior

The entity argument for validate_domain_name is only available in
FreeIPA 4.7 and later. This has been fixed using inspect to be able to
detect if entity is a valid argument. If not the whole realm name check
is skipped.

Related: #61 (ipaserver role - Fails on ipaclient install)
Fixes: #66 (Python 2 error with validate_domain)

roles/ipaclient/library/ipaclient_test.py

@@ -327,6 +327,9 @@ def main():
         validate_domain_name(options.domain_name)
 
         if options.realm_name:
+            argspec = inspect.getargspec(validate_domain_name)
+            if "entity" in argspec.args:
+                # NUM_VERSION >= 40690:
                 validate_domain_name(options.realm_name, entity="realm")
 
         ### ClientInstallInterface ###

roles/ipaserver/library/ipaserver_test.py

@@ -565,7 +565,9 @@ def main():
     if not options.realm_name:
         options.realm_name = options.domain_name
     options.realm_name = options.realm_name.upper()
-    if NUM_VERSION >= 40690:
+    argspec = inspect.getargspec(validate_domain_name)
+    if "entity" in argspec.args:
+        # NUM_VERSION >= 40690:
         try:
             validate_domain_name(options.realm_name, entity="realm")
         except ValueError as e: