Add try/finally to ensure we always reset the max jobs

src/Composer/Package/Version/VersionGuesser.php

@@ -311,6 +311,7 @@ class VersionGuesser
 
             $promises = [];
             $this->process->setMaxJobs(30);
+            try {
                 foreach ($branches as $candidate) {
                     $candidateVersion = Preg::replace('{^remotes/\S+/}', '', $candidate);
 
@@ -342,8 +343,10 @@ class VersionGuesser
                 }
 
                 $this->process->wait();
+            } finally {
                 $this->process->resetMaxJobs();
             }
+        }
 
         return array('version' => $version, 'pretty_version' => $prettyVersion);
     }