Comment 0 for bug 1838323

[Background]
Many packages are affected by the requirement to support the new era "Reiwa" (令和）

This is the meta bug to track packages that need fixes; which packages have already been SRUd to previous releases, how to prioritize the work needed, and general test cases for verifying that things are working as expected.

[Impact]
Users who run Ubuntu in Japanese.

[Test cases]

Unicode data include REIWA like it includes HEISEI. Reverse-build-depends need a rebuild to include the new data, followed by the following tests to make sure the data is taken into account.

== Character maps / font support ==

1) Search for character "SQUARE ERA NAME"
2) Verify that the results include at least "SQUARE ERA NAME HEISEI" and "SQUARE ERA NAME REIWA" (there should also be Syouwa, Taisyou and Meizi), and that the glyphs are readable:

 - SQUARE ERA NAME HEISEI: ㍻
 - SQUARE ERA NAME REIWA: 令和 (in a single glyph)

Display of the Reiwa square glyph is font-specific; it may show simply as a empty square or a square with hex characters. If that is the case, the unicode data supports the new character, but the selected font does not include the new glyph. Use fonts-noto-cjk to display the glyph.

[Regression potential]
This is a potentially large change as it impacts font display, character sets as well as date conversions. As such, extreme care should be taken to ensure that regressions are avoided, such that dates previous to May 1, 2019 continue to display as before, and dates onward are displayed with the new era symbols. The included test cases account for verifying the continued behavior or previous dates.