Fix error when calling shell script from browser

[Caprico85]

Description (*)

Running a shell script from browser may cause the PHP warning Undefined array key "argv". This happens because shell/abstract.php tries to read $_SERVER['argv'] without checking if it exists. $_SERVER['argv'] is not set when a script is run from browser.

I know running a shell script from browser doesn't make much sense and trying it will result in the message This script cannot be run from Browser. This is the shell script.. But nonetheless, the script should exit gracefully and not trigger a PHP warning.

Manual testing scenarios (*)

1. Open http://example.com/shell/indexer.php or any other shell script in your browser. Depending on your server settings you will see the warning.

Contribution checklist (*)

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All automated tests passed successfully (all builds are green)
• Add yourself to contributors list

[sreichel]

Why not

if (!isset($_SERVER['argv'])) {
    return $this;
}

[Caprico85]

Okay, maybe a bit more readable. I updated my PR.

I changed !isset to empty, so it also returns early when no parameters are given.

[justinbeaty]

I am not sure empty is correct. What about a custom shell script that extends the abstract class, but has no arguments?

edit: maybe not actually a problem since the script name is in argv as well IIRC.

[fballiano]

@justinbeaty I created a script and the run() method works correctly also with this patch, so I think the "empty" is not a problem in this context

[fballiano]

but actually... htaccess forbids to call shell/*.php from browser... so do we need this?

[justinbeaty]

I read it more carefully and see that it wouldn't cause any problems.

Regarding htaccess, I suppose it still doesn't hurt in case someone has a misconfigured server.

[fballiano]

merged and cherrypicked to v20