Fixing 'cd' function to use fish's 'cd' function and not the builtin command

plugins/cd/cd.fish

-function cd --description "Change working directory"
-  # Source a .rvmrc file in a directory after changing to it, if it exists.
-  # To disable this feature, set rvm_project_rvmrc=0 in $HOME/.rvmrc
+#
+# Source a .rvmrc file in a directory after changing to it, if it exists.
+# To disable this feature, set rvm_project_rvmrc=0 in $HOME/.rvmrc
+#
+function cd --description "Change directory"
+  redefine_function 'cd' "$__fish_datadir/functions/cd.fish" '
+    function cd --description "Change working directory"
+      old_cd "$argv"
 
-  builtin cd "$argv"
-  if test "$rvm_project_rvmrc" != 0
-    set -l cwd $PWD
-    while true
-      if contains $cwd "" $HOME "/"
-        if test "$rvm_project_rvmrc_default" = 1
-          rvm default 1>/dev/null 2>&1
-        end
-        break
-      else
-        if test -s ".rvmrc"
-          eval "rvm reload" > /dev/null
-          break
-        else
-          set cwd (dirname "$cwd")
+      if test "$rvm_project_rvmrc" != 0
+        set -l cwd $PWD
+        while true
+          if contains $cwd "" $HOME "/"
+            if test "$rvm_project_rvmrc_default" = 1
+              rvm default 1>/dev/null 2>&1
+            end
+            break
+          else
+            if test -s ".rvmrc"
+              eval "rvm reload" > /dev/null
+              break
+            else
+              set cwd (dirname "$cwd")
+            end
+          end
         end
+
+        set -e cwd
       end
     end
+'
 
-    set -e cwd
-  end
+  cd "$argv"
 end