bug #44479 [HttpClient] Double check if handle is complete (Nyholm)

This PR was squashed before being merged into the 4.4 branch.

Discussion
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[HttpClient] Double check if handle is complete

| Q             | A
| ------------- | ---
| Branch?       | 4.4
| Bug fix?      | yes
| New feature?  | no
| Deprecations? | no
| Tickets       |
| License       | MIT
| Doc PR        |

This is a forward compatibility fix. We did the same in Guzzle after a comment from bagder.

guzzle/guzzle#2892 (comment)

Basically, if libcurl decides to add an other value for `msg`, then our code will break without this PR. The only value for `msg` with current latest version of curl is `CURLMSG_DONE` which means that this is not a bugfix yet.. but it make sure that we respect the libcurl API.

Commits
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f35a6ad77e [HttpClient] Double check if handle is complete

Author: nicolas-grekas

Response/CurlResponse.php

@@ -277,6 +277,9 @@ private static function perform(ClientState $multi, array &$responses = null): v
             while (\CURLM_CALL_MULTI_PERFORM === curl_multi_exec($multi->handle, $active));
 
             while ($info = curl_multi_info_read($multi->handle)) {
+                if (\CURLMSG_DONE !== $info['msg']) {
+                    continue;
+                }
                 $result = $info['result'];
                 $id = (int) $ch = $info['handle'];
                 $waitFor = @curl_getinfo($ch, \CURLINFO_PRIVATE) ?: '_0';