http://lists.gnu.org/archive/html/bug-bash/2014-11/msg00178.html

diff --git a/arrayfunc.c b/arrayfunc.c
index 804e6da..0f900aa 100644
--- a/arrayfunc.c
+++ b/arrayfunc.c
@@ -498,7 +498,7 @@ assign_compound_array_list (var, nlist, flags)
 
   for (list = nlist; list; list = list->next)
     {
-      iflags = flags;
+      iflags = (flags & ~ASS_APPEND);
       w = list->word->word;
 
       /* We have a word of the form [ind]=value */