valid_ref 'heads/foo@bar'
invalid_ref 'heads/v@{ation'
invalid_ref 'heads/foo\bar'
+invalid_ref "$(printf 'heads/foo\t')"
+invalid_ref "$(printf 'heads/foo\177')"
+valid_ref "$(printf 'heads/fu\303\237')"
test_expect_success "check-ref-format --branch @{-1}" '
T=$(git write-tree) &&