exchange: reject new compression engines for v1 bundles (issue5506) Version 1 bundles only support a fixed set of compression engines. Before this change, we would accept any compression engine for v1 bundles, even those that may not work on v1. This could lead to an error. We define a fixed set of compression engines known to work with v1 bundles and we add checking to ensure a newer engine (like zstd) won't work with v1 bundles. I also took the liberty of adding test coverage for unknown compression names because I noticed we didn't have coverage of it before.

Issue351: mq: qrefresh can create extra revlog entry

  $ echo "[extensions]" >> $HGRCPATH
  $ echo "mq=" >> $HGRCPATH

  $ hg init
  $ hg qinit

  $ echo b > b
  $ hg ci -A -m foo
  adding b

  $ echo cc > b
  $ hg qnew -f foo.diff
  $ echo b > b
  $ hg qrefresh

  $ hg debugindex b
     rev    offset  length  ..... linkrev nodeid       p1           p2 (re)
       0         0       3  .....       0 1e88685f5dde 000000000000 000000000000 (re)