Fix regex

src/Composer/Repository/Vcs/GitDriver.php

@@ -170,7 +170,7 @@ class GitDriver extends VcsDriver implements VcsDriverInterface
         }
 
         // local filesystem
-        if (preg_match('{^(file://|/|[a-z]:[\\\\/])}', $url)) {
+        if (preg_match('{^(file://|/|[a-z]:[\\\\/])}i', $url)) {
             $process = new ProcessExecutor();
             // check whether there is a git repo in that path
             if ($process->execute(sprintf('cd %s && git show', escapeshellarg($url)), $output) === 0) {