WebSession: Prevent NPE in GitSmartHttpTools.isGitClient()

ContinuingHttpServletRequest doesn't have request URI. That cause

  public static boolean isInfoRefs(HttpServletRequest req) {
    return req.getRequestURI().endsWith(INFO_REFS_PATH)
    && VALID_SERVICES.contains(req.getParameter("service"));
  }

to throw NPE.

More robust implementation of isInfoRefs() could check for

  req.getRequestURI() != null

or swap the conditions.

Bug was filled against JGit project: [1].

[1] https://bugs.eclipse.org/bugs/show_bug.cgi?id=435404

Change-Id: Iac85505720496b411814a6d050a7612d507bf3a6

gerrit-httpd/src/main/java/com/google/gerrit/httpd/CacheBasedWebSession.java

@@ -68,7 +68,8 @@ public abstract class CacheBasedWebSession implements WebSession {
     this.anonymousProvider = anonymousProvider;
     this.identified = identified;
 
-    if (!GitSmartHttpTools.isGitClient(request)) {
+    if (request.getRequestURI() == null
+        || !GitSmartHttpTools.isGitClient(request)) {
       String cookie = readCookie();
       if (cookie != null) {
         key = new Key(cookie);