Re: Time to drop plpython2?

I see you have posted a patch for this in the meson thread 
(https://www.postgresql.org/message-id/attachment/127770/v5-0003-plpython-Drop-support-python2.patch). 
  Here is my review of that.

I would change the search order in configure from

PGAC_PATH_PROGS(PYTHON, [python python3 python2])

to

PGAC_PATH_PROGS(PYTHON, [python3 python])

This makes sure you don't accidentally pick up a "python" binary that 
points to Python 2.  This would otherwise immediately generate lots of 
build failures on older platforms that still have Python 2 around.

You left two FIXME sections in plpython.h.  AFAICT, we can make the 
substitutions corresponding to those #define's in the source code and 
remove those blocks.

src/pl/plpython/expected/README should be updated for the removed files.

Some documentation updates are needed.  I see possibly relevant text in 
the following files:

hstore.sgml
install-windows.sgml
installation.sgml
json.sgml
libpq.sgml
plpython.sgml
ref/comment.sgml (examples)
ref/create_transform.sgml (examples)
ref/drop_transform.sgml (examples)
standalone-profile.xsl

src/tools/msvc/ has lots of Python-related content.

More stuff to clean up:

contrib/hstore_plpython/.gitignore
contrib/jsonb_plpython/.gitignore
contrib/ltree_plpython/.gitignore
src/pl/plpython/.gitignore

Finally, morally related, there is some Python 2/3 compat code in 
contrib/unaccent/generate_unaccent_rules.py that could be removed. 
Also, arguably, change the shebang line in that script.