patch: show lower-ed translated message correctly Before this patch, patch.filterpatch() shows meaningless translation of help message for chunk selection in some encoding. It applies str.lower() instead of encoding.lower(str) on translated message, but some encoding uses 0x41(A) - 0x5a(Z) as the second or later byte of multi-byte character (for example, ja_JP.cp932), and str.lower() causes unexpected result. To show lower-ed translated message correctly, this patch replaces str.lower() by encoding.lower(str).