i18n-ja: synchronized with
b357a972d6cd
minirst: use unicode string as intermediate form for replacement
# this change redones part of
521c8e0c93bf, backed out by
0ad0ebe67815
Some character encodings use ASCII characters other than
control/alphabet/digit as a part of multi-bytes characters, so direct
replacing with such characters on strings in local encoding causes
invalid byte sequences.
[mpm: test changed to simple doctest]