Improve an error message.
Improve an error message.

Patch by: David Glasser <glasser@mit.edu>

* subversion/libsvn_wc/adm_ops.c
  (svn_wc_add2): Clarify node type change error message to not imply that the
  next step must be to "commit the deletion", which may have already occurred.


git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@860959 13f79535-47bb-0310-9956-ffa450edef68

YueLinHo/Subversion,wbond/subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,wbond/subversion,wbond/subversion,wbond/subversion,wbond/subversion,YueLinHo/Subversion,wbond/subversion,wbond/subversion,YueLinHo/Subversion