Don't add an empty path component on trailing slash.

c++/src/kj/compat/url-test.c++

@@ -294,6 +294,18 @@ KJ_TEST("parse / stringify URL") {
   // "." and ".." are still processed, though.
   parseAndCheck("https://capnproto.org/foo//../bar/.",
                 "https://capnproto.org/foo/bar/", ALLOW_EMPTY);
+
+  {
+    auto url = parseAndCheck("https://foo/", nullptr, ALLOW_EMPTY);
+    KJ_EXPECT(url.path.size() == 0);
+    KJ_EXPECT(url.hasTrailingSlash);
+  }
+
+  {
+    auto url = parseAndCheck("https://foo/bar/", nullptr, ALLOW_EMPTY);
+    KJ_EXPECT(url.path.size() == 1);
+    KJ_EXPECT(url.hasTrailingSlash);
+  }
 }
 
 KJ_TEST("URL percent encoding") {

c++/src/kj/compat/url.c++

@@ -233,7 +233,8 @@ Maybe<Url> Url::tryParse(StringPtr text, Context context, Options options) {
         result.path.removeLast();
       }
       result.hasTrailingSlash = true;
-    } else if ((part.size() == 0 && !options.allowEmpty) || (part.size() == 1 && part[0] == '.')) {
+    } else if ((part.size() == 0 && (!options.allowEmpty || text.size() == 0)) ||
+               (part.size() == 1 && part[0] == '.')) {
       // Collapse consecutive slashes and "/./".
       result.hasTrailingSlash = true;
     } else {