Use regex to capture git version.

src/Composer/Util/Git.php

@@ -282,9 +282,9 @@ class Git
         if (0 !== $this->process->execute('git --version', $output)) {
             throw new \RuntimeException(self::sanitizeUrl('Failed retrieve git version, git was not found, check that it is installed and in your PATH env.' . "\n\n" . $this->process->getErrorOutput()));
         }
-        if (strpos($output, 'git version ') === FALSE) {
+        if (preg_match('/^git version (.*)/', $output, $matches) !== 1) {
             throw new \RuntimeException('git --version output seems to have changed, expected "git version x.y.z".');
         }
-        return substr($output, 12);
+        return $matches[1];
     }
 }