help: search section of help topic by translated section name correctly Before this patch, "hg help topic.section" might show unexpected section of help topic in some encoding. It applies str.lower() instead of encoding.lower(str) on translated message to search section case-insensitively, 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 search section of help topic by translated section name correctly, this patch replaces str.lower() by encoding.lower(str) for both query string (in commands.help()) and translated help text (in minirst.getsections()).