Description of problem:

If the dwh database is inaccessible, e.g. because the credentials were changed or because it's down/corrupted/etc., engine-cleanup fails.

It emits:

[WARNING] Cannot connect to DWH database using existing credentials: ovirt_engine_history@localhost:5432

And then:

[ ERROR ] Failed to execute stage 'Misc configuration': 'NoneType' object is not iterable

setup log has:

2017-12-28 12:54:39,743+0200 DEBUG otopi.context context._executeMethod:128 Stage misc METHOD otopi.plugins.ovirt_engine_common.ovirt_engine_dwh.db.pgpass.Plugin._misc
2017-12-28 12:54:39,744+0200 DEBUG otopi.context context._executeMethod:143 method exception
Traceback (most recent call last):
  File "/usr/lib/python2.7/site-packages/otopi/context.py", line 133, in _executeMethod
    method['method']()
  File "/usr/share/ovirt-engine/setup/bin/../plugins/ovirt-engine-common/ovirt-engine-dwh/db/pgpass.py", line 57, in _misc
    dbenvkeys=odwhcons.Const.DWH_DB_ENV_KEYS,
  File "/usr/share/ovirt-engine/setup/ovirt_engine_setup/engine_common/database.py", line 357, in createPgPass
    ':\\',
  File "/usr/lib/python2.7/site-packages/ovirt_engine/util.py", line 45, in escape
    for c in s:
TypeError: 'NoneType' object is not iterable

Version-Release number of selected component (if applicable):

Current master, probably much before

How reproducible:
Always

Steps to Reproduce:
1. engine-setup, configure dwh
2. Change dwh db password
3. engine-cleanup

Actual results:
Fails as above

Expected results:
Succeeds

Additional info:

engine-cleanup deliberately has a code to emit the above warning instead of failing (which is what engine-setup does), but then fails later on.

This does not affect the engine database - if it's inaccessible, engine-cleanup emits a warning:

[WARNING] Cannot connect to Engine database using existing credentials: engine@localhost:5432

But then continues and finishes successfully (but without cleaning up the database).

It's not an important bug. Filing it mainly because I ran into it already several times during development, and the error message is cryptic.