Testcase for #628

mysql-test/r/func_misc.result:
  Appropriate result
mysql-test/t/func_misc.test:
  Test case added

mysql-test/r/func_misc.result

@@ -13,3 +13,6 @@ NULL	255.255.1.255	0.0.1.255
 select length(format('nan', 2)) > 0;
 length(format('nan', 2)) > 0
 1
+select concat("$",format(2500,2));
+concat("$",format(2500,2))
+$2,500.00

mysql-test/t/func_misc.test

@@ -12,3 +12,8 @@ select inet_ntoa(1099511627775),inet_ntoa(4294902271),inet_ntoa(511);
 # Test for core dump with nan
 #
 select length(format('nan', 2)) > 0;
+
+#
+# Test for bug #628
+#
+select concat("$",format(2500,2));