I applied this patch on two machines, the first one have this issue and the second one works perfectly without this patch.
After applying this patch, these two machines work now perfectly, the issue mentioned doesn't occur and we have not regression bugs.

Thanks for your job.

Thanks for the PR!

I would rather deal with the source of the issue instead of removing the exec from the hook template since it is there for a reason.
Can you give me some additional information about systems that are adding those second "exec" statement? (OS, PHP version, composer show, ...) I was not able to reproduce.

It looks like this additional exec is added by the Symfony Process component here in this PR: symfony/symfony#21474
This issue mentions the break: symfony/symfony#22476
And a PR is on it's way: symfony/symfony#22476

So I am not sure this is something that needs to be fixed in this repo.

You're right, it's due to my symfony/process version which is the mentioned 3.3 :)
And you're right, it's not the responsibility of this repo to fix it.

I am fine with closing this PR. I will just use my fork until process is fixed.

Alright, I'll close this one.
You could also copy the adjusted hook templates to your project and use the hooks_dir parameter (https://github.com/phpro/grumphp/blob/master/doc/parameters.md) . This way you don't have to maintain your own patch.

@veewee even better. Thanks for mentioning it!