[HttpClient] fix proxied redirects in curl client

[matthi4s]

Q	A
Branch?	5.4
Bug fix?	yes
New feature?	no
Deprecations?	no
Tickets	-
License	MIT
Doc PR	-

When using the CurlHttpClient with a proxy defined using the options array, the proxy isn't used after the first request on redirects. The CURLOPT_PROXY option is overwritten in the redirect resolver, but the $options variable isn't present in that case which causes it to be overwritten with environment variables or nothing, which disables the proxy.

I don't know why the proxy option gets rewritten with every redirect, since the same curl handle is used, it should not be necessary to set it again. It also wasn't set before the original commit which introduced this bug (9e5305e). I've removed that part, but I can also change it to pass on the reference to the $options variable, which also fixes the issue. In that case, I would suggest moving the validation of the environment variable to a separate function to avoid duplicating that part.

I've also added a test case that fails for the curl client without the fix but succeeds for the other clients and the curl client with both possible fixes.

[carsonbot]

Hey!

I see that this is your first PR. That is great! Welcome!

Symfony has a contribution guide which I suggest you to read.

In short:

• Always add tests
• Keep backward compatibility (see https://symfony.com/bc).
• Bug fixes must be submitted against the lowest maintained branch where they apply (see https://symfony.com/releases)
• Features and deprecations must be submitted against the 6.3 branch.

Review the GitHub status checks of your pull request and try to solve the reported issues. If some tests are failing, try to see if they are failing because of this change.

When two Symfony core team members approve this change, it will be merged and you will become an official Symfony contributor!
If this PR is merged in a lower version branch, it will be merged up to all maintained branches within a few days.

I am going to sit back now and wait for the reviews.

Cheers!

Carsonbot

[nicolas-grekas]

LGTM thanks. Here are some nitpicking. Failures are false positives.

[fabpot]

Thank you @matthi4s.