Ruby

string.c: fix up r58703

• string.c (rb_external_str_new_with_enc): fix the case of
  conversion failure. when conversion failed for some reason,
  just ignores the default internal encoding and returns in the
  given encoding.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@58705 b2dd03c8-39d4-4d8f-98ff-823fe69b080e