Fix typo to avoid traceback during testing

* When iterating over a child state, a failure should be propagated
  up so parent blocks don't continue iterating
* Make sure a child state exists before trying to search it

Fixes #12210

Python 3: avoid iteritems() in a template

I don't think six.iteritems is available here, but I also don't expect
there to be enough platforms to ever make the speed difference between
.items() and .iteritems() noticeable.

Simplify FactCache.copy()

Also fix the bug (missing from six import iteritems) I introduced in
823677b4.

Replace .iteritems() with six.iteritems()

Replace .iteritems() with six.iteritems() everywhere except in
module_utils (because there's no 'six' on the remote host).  And except
in lib/ansible/galaxy/data/metadata_template.j2, because I'm not sure
six is available there.

Merge branch 'connection-locking' of https://github.com/amenonsen/ansible into amenonsen-connection-locking

Make lock_host_keys a real noop, instead of half-a-noop

The lock file is (a temporary file) opened in the parent process, whose
open fd is inherited by the workers after fork, and passed down through
the PlayContext. Connection grows lock/unlock methods which can be used
by individual connection plugins.

Right now, we don't do any locking, but we still scan known_hosts files
twice per connection. That's completely unnecessary, and the proposed
solutions to the locking problem wouldn't need known_hosts scanning
anyway, so this code can go away.

Delete all compiled python files when running hacking/env-setup

In v1, a trailing newline was kept if the parameter was passed as key=value.  If
the parameter was passed as yaml dict the trailing newline was
discarded.  Since key-value and yaml dict were unified in v2 we have to
make a choice as to which behaviour we want.  Decided that keeping trailing
newlines by default made the most sense.

Fixes #12200
Fixes #12199

Use rich comparisons for Attribute and FieldAttribute

Fixes #12206

  ansible is passing unicode arond internally so we should test the same
  data.
* Add a zero length test for _count_newlines and fix the zero newlines
  test to have no newlines.

Fix for one half of hte bug reported in #12198