FIX Let admin sections have same url-segment-prefix (#1974)

React admin section routing shouldn't kick in when the URL segment for
an admin section starts with the same string, unless it's actually part
of that same section.

Author: GuySartorelli

behat.yml

@@ -21,6 +21,9 @@ default:
         -
           SilverStripe\BehatExtension\Context\FixtureContext:
             - '%paths.modules.admin%/tests/behat/features/files/'
+        -
+          SilverStripe\Framework\Tests\Behaviour\ConfigContext:
+            - '%paths.modules.admin%/tests/behat/features/files/'
 
   extensions:
     SilverStripe\BehatExtension\MinkExtension:

client/dist/js/bundle.js

@@ -98,7 +98,7 @@ class BootRoutes {
 
       // Check if the beginning of the route is the same as the current location.
       // Since we haven't decided on a router yet, we can't use it for route matching.
-      return currentPath.match(route);
+      return currentPath.match(`${route}(/|$)`);
     });
   }
 

client/src/boot/BootRoutes.js

@@ -0,0 +1,15 @@
+@retry @job2
+Feature: Single-page routing works as expected
+  As a content author
+  I want to single-page-routing to work as expected
+  So that I can get to the areas I want to get to
+
+  Background:
+    Given I have a config file "fake-asset-admin.yml"
+      And the "Employee" "Employee A" with "Email"="test@example.com" and "Biography"="<p>some content here</p>" and "DateOfBirth"="1990-06-09"
+      And the "group" "EDITOR" has permissions "Access to 'Test ModelAdmin' section" and "TEST_DATAOBJECT_EDIT"
+      And I am logged in as a member of "EDITOR" group
+
+  Scenario: Admin sections can start with the same string as a react section
+    When I go to "/admin/assets-test"
+    Then I should see "Add Company"

tests/behat/features/admin-routing.feature

@@ -0,0 +1,5 @@
+---
+Name: fake-asset-admin
+---
+TestModelAdmin:
+  url_segment: 'assets-test'