t4018-diff-funcname: demonstrate end of line funcname matching flaw

Since the newline is not removed from lines before pattern matching, a
pattern cannot match to the end of the line using the '$' operator without
using an additional operator which will indirectly match the '\n' character.

Introduce a test which should pass, but which does not due to this flaw.
Signed-off-by: NBrandon Casey <drafnel@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

t/t4018-diff-funcname.sh

@@ -69,6 +69,12 @@ test_expect_success 'last regexp must not be negated' '
 	grep "fatal: Last expression must not be negated:"
 '
 
+test_expect_failure 'pattern which matches to end of line' '
+	git config diff.java.funcname "Beer$" &&
+	git diff --no-index Beer.java Beer-correct.java |
+	grep "^@@.*@@ Beer"
+'
+
 test_expect_success 'alternation in pattern' '
 	git config diff.java.xfuncname "^[ 	]*((public|static).*)$" &&
 	git diff --no-index Beer.java Beer-correct.java |