issue1079_test: fix probe text assertion

Asserting for the following newline leaves us vulnerable to a race
where the probe text is printed, but the newline and bash prompt haven't.

issue1079_test.go

@@ -255,7 +255,7 @@ func TestIssue1079_bashPTYLosesFirstTypedByte(t *testing.T) {
 			output := buffer.String()
 			t.Logf("probe output:\n%s", output)
 			assert.NotContains(t, output, "command not found")
-			assert.Contains(t, output, probeText+"\n")
+			assert.Contains(t, output, probeText)
 		})
 	}
 }