Deploy hook not found when module name contains _deploy

[pfrenssen]

Describe the bug
This was originally reported in #5112 by @idiazroncero.

I noticed a rather specific error when the module's name contains the substring _deploy on its name.

Take mymodule_deploy as an example, with a mymodule_deploy_deploy_myfunction deploy hook and a mymodule_deploy.deploy.php file.

Running drush deploy:hook will fail with the following error:

[warning] Deploy hook function mymodule_deploy_deploy_myfunction not found in file mymodule.deploy.php

This is because list($module, $name) = explode('_deploy_', $function, 2); will set $module to just mymodule and not mymodule_deploy and, thus, the $filename will be wrong.

This is an uncommon but not rare scenario. In fact, it happened to me because I had a separate custom module dedicated to deploy hooks that had the deploy substring on the name.

To Reproduce

• Create a module named myproject_deploy.
• Create a myproject_deploy.deploy.php file which has a deploy function named myproject_deploy_deploy_my_update().
• Run drush deploy

Expected behavior
Deploy hook is executed normally.

Actual behavior

 [warning] Deploy hook function myproject_deploy_deploy_my_update not found in file myproject.deploy.php
 [error]  Deploy hook failed: myproject_deploy_deploy_my_update
 [error]  Update aborted by: myproject_deploy_deploy_my_update