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).

mercurial/patch.py

@@ -1010,7 +1010,7 def filterpatch(ui, headers, operation=N
             ui.write("\n")
             if r == 8: # ?
                 for c, t in ui.extractchoices(resps)[1]:
-                    ui.write('%s - %s\n' % (c, t.lower()))
+                    ui.write('%s - %s\n' % (c, encoding.lower(t)))
                 continue
             elif r == 0: # yes
                 ret = True

tests/test-commit-interactive.t

@@ -878,6 +878,32 Help, quit
   abort: user quit
   [255]
 
+#if gettext
+
+Test translated help message
+
+str.lower() instead of encoding.lower(str) on translated message might
+make message meaningless, because some encoding uses 0x41(A) - 0x5a(Z)
+as the second or later byte of multi-byte character.
+
+For example, "\x8bL\x98^" (translation of "record" in ja_JP.cp932)
+contains 0x4c (L). str.lower() replaces 0x4c(L) by 0x6c(l) and this
+replacement makes message meaningless.
+
+This tests that translated help message is lower()-ed correctly.
+
+  $ LANGUAGE=ja
+  $ export LANGUAGE
+
+  $ hg commit -i --encoding cp932 2>&1 <<EOF | grep '^y - '
+  > ?
+  > q
+  > EOF
+  y - \x82\xb1\x82\xcc\x95\xcf\x8dX\x82\xf0\x8bL\x98^(yes) (esc)
+
+  $ LANGUAGE=
+#endif
+
 Skip
 
   $ hg commit -i <<EOF