Add a comment about a vim test failure

git-svn-id: http://svn.linuxfromscratch.org/LFS/trunk/BOOK@11233 4aa44e1e-78dd-0310-a6d2-fbcd4c07a689

chapter06/vim.xml

@@ -63,7 +63,8 @@
     <para>However, this test suite outputs a lot of binary data to the screen,
     which can cause issues with the settings of the current terminal. This can
     be resolved by redirecting the output to a log file.  A successful test
-    will result in the words "ALL DONE" at completion.</para>
+    will result in the words "ALL DONE" at completion. One test, 
+    Test_recover_root_dir() is known to fail, but is harmless.</para>
 
     <para>Install the package:</para>