Steps to reproduce the issue

Install joomla with cache Redis enabled.

Go to joomla folder and run php -f cli/update_cron.php

I get result:

Error displaying the error page: Application Instantiation Error: Application Instantiation Error

Expected result

Script works without errors

Actual result

Get exception message.

System information (as much as possible)

PHP 7.0 and 7.1 - not revelant
Joomla 3.7.3-dev and olders
Redis as cache handler and System Cache ON

Additional comments

The error comes from https://github.com/joomla/joomla-cms/blob/staging/libraries/joomla/factory.php#L122

and it starts at https://github.com/joomla/joomla-cms/blob/staging/libraries/joomla/cache/storage/redis.php#L67

Can we break B/C by removing $app = JFactory::getApplication(); and replacing
JError::raiseWarning(500, 'Redis connection failed');
by throw new JCacheExceptionConnecting('Could not connect to redis server');
in redis handler?

If yes then I can write PR.