Make the default Ansible_managed string static so it doesn't interfere with idempotency

examples/ansible.cfg

@@ -125,8 +125,9 @@
 # templates indicates to users editing templates files will be replaced.
 # replacing {file}, {host} and {uid} and strftime codes with proper values.
 #ansible_managed = Ansible managed: {file} modified on %Y-%m-%d %H:%M:%S by {uid} on {host}
-# This short version is better used in templates as it won't flag the file as changed every run.
+# {file}, {host}, {uid}, and the timestamp can all interfere with idempotence
-#ansible_managed = Ansible managed: {file} on {host}
+# in some situations so the default is a static string:
+#ansible_managed = Ansible managed
 
 # by default, ansible-playbook will display "Skipping [host]" if it determines a task
 # should not be run on a host.  Set this to "False" if you don't want to see these "Skipping"

lib/ansible/constants.py

@@ -193,7 +193,7 @@ DEFAULT_VAULT_PASSWORD_FILE = get_config(p, DEFAULTS, 'vault_password_file', 'AN
 DEFAULT_TRANSPORT         = get_config(p, DEFAULTS, 'transport',        'ANSIBLE_TRANSPORT',        'smart')
 DEFAULT_SCP_IF_SSH        = get_config(p, 'ssh_connection', 'scp_if_ssh',       'ANSIBLE_SCP_IF_SSH',       'smart')
 DEFAULT_SFTP_BATCH_MODE   = get_config(p, 'ssh_connection', 'sftp_batch_mode', 'ANSIBLE_SFTP_BATCH_MODE', True, value_type='boolean')
-DEFAULT_MANAGED_STR       = get_config(p, DEFAULTS, 'ansible_managed',  None,           'Ansible managed: {file} modified on %Y-%m-%d %H:%M:%S by {uid} on {host}')
+DEFAULT_MANAGED_STR       = get_config(p, DEFAULTS, 'ansible_managed',  None,           'Ansible managed')
 DEFAULT_SYSLOG_FACILITY   = get_config(p, DEFAULTS, 'syslog_facility',  'ANSIBLE_SYSLOG_FACILITY', 'LOG_USER')
 DEFAULT_KEEP_REMOTE_FILES = get_config(p, DEFAULTS, 'keep_remote_files', 'ANSIBLE_KEEP_REMOTE_FILES', False, value_type='boolean')
 DEFAULT_HASH_BEHAVIOUR    = get_config(p, DEFAULTS, 'hash_behaviour', 'ANSIBLE_HASH_BEHAVIOUR', 'replace')