This problem has already been fixed by one of the previous changes.

Adding test case to cover queries which worked incorrectly earlier:
Bug#18321: Can't store EuroSign with latin1_german1_ci and latin1_general_ci

mysql-test/r/ctype_latin1.result

@@ -369,3 +369,25 @@ ERROR 42000: You have an error in your SQL syntax; check the manual that corresp
 SELECT 'a' as str;
 str
 a
+set @str= _latin1 'ABC ߲~    @ abc';
+SELECT convert(@str collate latin1_bin using utf8);
+convert(@str collate latin1_bin using utf8)
+ABC ߲~    @ abc
+SELECT convert(@str collate latin1_general_ci using utf8);
+convert(@str collate latin1_general_ci using utf8)
+ABC ߲~    @ abc
+SELECT convert(@str collate latin1_german1_ci using utf8);
+convert(@str collate latin1_german1_ci using utf8)
+ABC ߲~    @ abc
+SELECT convert(@str collate latin1_danish_ci using utf8);
+convert(@str collate latin1_danish_ci using utf8)
+ABC ߲~    @ abc
+SELECT convert(@str collate latin1_spanish_ci using utf8);
+convert(@str collate latin1_spanish_ci using utf8)
+ABC ߲~    @ abc
+SELECT convert(@str collate latin1_german2_ci using utf8);
+convert(@str collate latin1_german2_ci using utf8)
+ABC ߲~    @ abc
+SELECT convert(@str collate latin1_swedish_ci using utf8);
+convert(@str collate latin1_swedish_ci using utf8)
+ABC ߲~    @ abc

mysql-test/t/ctype_latin1.test

@@ -95,4 +95,18 @@ SET collation_connection='latin1_bin';
 CREATE TABLE a (a int);
 SELECT 'a' as str;
 
+
+#
+# Bug#18321: Can't store EuroSign with latin1_german1_ci and latin1_general_ci
+# The problem was in latin1->utf8->latin1 round trip.
+#
+set @str= _latin1 'ABC ߲~    @ abc';
+SELECT convert(@str collate latin1_bin using utf8);
+SELECT convert(@str collate latin1_general_ci using utf8);
+SELECT convert(@str collate latin1_german1_ci using utf8);
+SELECT convert(@str collate latin1_danish_ci using utf8);
+SELECT convert(@str collate latin1_spanish_ci using utf8);
+SELECT convert(@str collate latin1_german2_ci using utf8);
+SELECT convert(@str collate latin1_swedish_ci using utf8);
+
 # End of 4.1 tests