RFR: 755: Anything starting with a "/" is treated as a command

[Erik Joelsson]

On Fri, 24 Feb 2023 16:02:06 GMT, Kevin Rushforth <kcr at openjdk.org> wrote:

> See for example this PR and corresponding email:
> 
> [openjdk/jdk#12695](https://github.com/openjdk/jdk/pull/12695) https://mail.openjdk.org/pipermail/build-dev/2023-February/037829.html
> 
> I'm not sure why the PR bot didn't reply to that instance though.

I figured out why this was filtered in the email but not interpreted as a command in PR bot. The regex is different. In mlbridge, there is no matching of space between the command and the optional arguments. One way we could reduce false positives is to further restrict the regex. Stop accepting capital letters, as we only have lower case commands, and make sure the regex in the different bots match (maybe even unify them into one location in the common module).

Another pattern I saw in the search was a user using `/keepalive` in a comment to stop the bot from auto closing the PR. He probably knows it's an invalid command, but by using an invalid command, there is no email sent, which is actually a feature in this case.

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PR: https://git.openjdk.org/skara/pull/1479