Bug #3131 mysqltest fails on $2=$1 assignment in test

client/mysqltest.c:
  Fix function var_copy to make it possible to assign one variable to another. 
  ex: let $1=$2
mysql-test/r/mysqltest.result:
  Update test result
mysql-test/t/mysqltest.test:
  Add test cases for variable to variable assignment

client/mysqltest.c

@@ -1147,16 +1147,24 @@ int var_query_set(VAR* v, const char *p, const char** p_end)
   return 0;
 }
 
-void var_copy(VAR* dest, VAR* src)
+void var_copy(VAR *dest, VAR *src)
 {
-  dest->int_val=src->int_val;
-  dest->int_dirty=src->int_dirty;
+  dest->int_val= src->int_val;
+  dest->int_dirty= src->int_dirty;
+
+  /* Alloc/realloc data for str_val in dest */
   if (dest->alloced_len < src->alloced_len &&
-      !(dest->str_val=my_realloc(dest->str_val,src->alloced_len+1,
-				 MYF(MY_WME))))
+      !(dest->str_val= dest->str_val
+        ? my_realloc(dest->str_val, src->alloced_len, MYF(MY_WME))
+        : my_malloc(src->alloced_len, MYF(MY_WME))))
     die("Out of memory");
-  dest->str_val_len=src->str_val_len;
-  memcpy(dest->str_val,src->str_val,src->str_val_len+1);
+  else
+    dest->alloced_len= src->alloced_len;
+
+  /* Copy str_val data to dest */
+  dest->str_val_len= src->str_val_len;
+  if (src->str_val_len)
+    memcpy(dest->str_val, src->str_val, src->str_val_len);
 }
 
 int eval_expr(VAR* v, const char *p, const char** p_end)

mysql-test/r/mysqltest.result

@@ -206,6 +206,13 @@ source database
 hej
 hej 
 hej
+1
+
+
+a long variable content
+a long variable content
+a long $where variable content
+
 mysqltest: At line 1: Missing arguments to let
 mysqltest: At line 1: Missing variable name in let
 mysqltest: At line 1: Variable name in hi=hi does not start with '$'

mysql-test/t/mysqltest.test

@@ -473,6 +473,26 @@ echo $1;
 let $1 = hej;
 echo $1;
 
+let $1=1;
+let $2=$1;
+echo $2;
+let $5=$6;
+echo $5;
+echo $6;
+
+let $where=a long variable content;
+echo $where;
+
+let $where2= $where;
+echo $where2;
+
+let $where3=a long $where variable content;
+echo $where3;
+
+let $novar1= $novar2;
+echo $novar1;
+
+
 
 # Test illegal uses of let