fix redirect when project is installed in subdirectory

web/.htaccess

@@ -8,6 +8,16 @@ DirectoryIndex app.php
 <IfModule mod_rewrite.c>
     RewriteEngine On
 
+    # Determine the RewriteBase automatically and set it as environment variable.
+    # If you are using Apache aliases to do mass virtual hosting or installed the
+    # project in a subdirectory, the base path will be prepended to allow proper
+    # resolution of the app.php file and to redirect to the correct URI. It will
+    # work in environments without path prefix as well, providing a safe, one-size
+    # fits all solution. But as you do not need it in this case, you can comment
+    # the following 2 lines to eliminate the overhead.
+    RewriteCond %{REQUEST_URI}::$1 ^(/.+)/(.+)::\2$
+    RewriteRule ^(.*) - [E=BASE:%1]
+
     # Redirect to URI without front controller to prevent duplicate content
     # (with and without `/app.php`). Only do this redirect on the initial
     # rewrite by Apache and not on subsequent cycles. Otherwise we would get an
@@ -20,21 +30,15 @@ DirectoryIndex app.php
     # - use Apache >= 2.3.9 and replace all L flags by END flags and remove the
     #   following RewriteCond (best solution)
     RewriteCond %{ENV:REDIRECT_STATUS} ^$
-    RewriteRule ^app\.php(/(.*)|$) %{CONTEXT_PREFIX}/$2 [R=301,L]
+    RewriteRule ^app\.php(/(.*)|$) %{ENV:BASE}/$2 [R=301,L]
 
     # If the requested filename exists, simply serve it.
     # We only want to let Apache serve files and not directories.
     RewriteCond %{REQUEST_FILENAME} -f
     RewriteRule .? - [L]
 
-    # The following rewrites all other queries to the front controller. The
-    # condition ensures that if you are using Apache aliases to do mass virtual
-    # hosting, the base path will be prepended to allow proper resolution of the
-    # app.php file; it will work in non-aliased environments as well, providing
-    # a safe, one-size fits all solution.
-    RewriteCond %{REQUEST_URI}::$1 ^(/.+)(.+)::\2$
-    RewriteRule ^(.*) - [E=BASE:%1]
-    RewriteRule .? %{ENV:BASE}app.php [L]
+    # Rewrite all other queries to the front controller.
+    RewriteRule .? %{ENV:BASE}/app.php [L]
 </IfModule>
 
 <IfModule !mod_rewrite.c>