This is to cherry-pick a fix for
  http://bugs.icu-project.org/trac/ticket/12130

It's done by merging commit '2b12f877' (for m49 branch) to
master. (ICU's m49 branch was fixed first because ICU master was
in the middle of upgrading to ICU 56.1).

BUG=575206
TEST=See comment 51 in the bug
TBR=mmoroz@chromium.org

Review URL: https://codereview.chromium.org/1662453002 .