fix handling of post authentication filters for protocol request

do not call PushStateDispatcher in the HttpProtocolServletAuthenticationFilter,
because the HttpProtocolServlet already does this.

scm-webapp/src/test/java/sonia/scm/web/filter/HttpProtocolServletAuthenticationFilterTest.java

@@ -0,0 +1,72 @@
+package sonia.scm.web.filter;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.Mock;
+import org.mockito.junit.jupiter.MockitoExtension;
+import sonia.scm.config.ScmConfiguration;
+import sonia.scm.util.HttpUtil;
+import sonia.scm.web.UserAgent;
+import sonia.scm.web.UserAgentParser;
+import sonia.scm.web.WebTokenGenerator;
+
+import javax.servlet.FilterChain;
+import javax.servlet.ServletException;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+import java.io.IOException;
+import java.util.Collections;
+import java.util.Set;
+
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+@ExtendWith(MockitoExtension.class)
+class HttpProtocolServletAuthenticationFilterTest {
+
+  private ScmConfiguration configuration = new ScmConfiguration();
+
+  private Set<WebTokenGenerator> tokenGenerators = Collections.emptySet();
+
+  @Mock
+  private UserAgentParser userAgentParser;
+
+  private HttpProtocolServletAuthenticationFilter authenticationFilter;
+
+  @Mock
+  private HttpServletRequest request;
+
+  @Mock
+  private HttpServletResponse response;
+
+  @Mock
+  private FilterChain filterChain;
+
+  private UserAgent nonBrowser = UserAgent.builder("i'm not a browser").browser(false).build();
+  private UserAgent browser = UserAgent.builder("i am a browser").browser(true).build();
+
+  @BeforeEach
+  void setUpObjectUnderTest() {
+    authenticationFilter = new HttpProtocolServletAuthenticationFilter(configuration, tokenGenerators, userAgentParser);
+  }
+
+  @Test
+  void shouldSendUnauthorized() throws IOException, ServletException {
+    when(userAgentParser.parse(request)).thenReturn(nonBrowser);
+
+    authenticationFilter.handleUnauthorized(request, response, filterChain);
+
+    verify(response).sendError(HttpServletResponse.SC_UNAUTHORIZED, HttpUtil.STATUS_UNAUTHORIZED_MESSAGE);
+  }
+
+  @Test
+  void shouldCallFilterChain() throws IOException, ServletException {
+    when(userAgentParser.parse(request)).thenReturn(browser);
+
+    authenticationFilter.handleUnauthorized(request, response, filterChain);
+
+    verify(filterChain).doFilter(request, response);
+  }
+
+}