Redirect using path-based URL

Do not use a full URL when redirecting at first login because it
could be at time incorrect.

When running Gerrit from inside a container, Docker itself acts as
an HTTP reverse proxy and the actual external hostname would be
different.

Change-Id: I6be4d09902b4f1998575d40daa65ddf9fb0f0d26

src/main/java/com/googlesource/gerrit/plugins/manager/FirstWebLoginListener.java

diff --git a/src/main/java/com/googlesource/gerrit/plugins/manager/FirstWebLoginListener.java b/src/main/java/com/googlesource/gerrit/plugins/manager/FirstWebLoginListener.java
index 0d18bd6..85dbdd2 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/manager/FirstWebLoginListener.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/manager/FirstWebLoginListener.java
@@ -22,6 +22,7 @@
 import com.google.inject.Inject;
 
 import java.io.IOException;
+import java.net.URI;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.StandardOpenOption;
@@ -41,7 +42,7 @@
       @PluginCanonicalWebUrl String pluginUrl) {
     this.pluginData = pluginData;
     this.pluginLoader = pluginLoader;
-    this.pluginUrl = pluginUrl;
+    this.pluginUrl = urlPath(pluginUrl);
   }
 
   @Override
@@ -64,4 +65,8 @@
   public void onLogout(IdentifiedUser user, HttpServletRequest request,
       HttpServletResponse response) {
   }
+
+  private static String urlPath(String url) {
+    return URI.create(url).getPath();
+  }
 }