tests/test-username-newline.t

phases: allow registration and boundary advancement with revision sets

The core internals either use revision sets already or can trivially use
them. Use the new interface in cg1unpacker.apply to avoid materializing
the list of all new nodes as it is normally just a revision range. This
avoids about 67 Bytes / changeset on AMD64 in peak RSS.

Differential Revision: https://phab.mercurial-scm.org/D9232

  $ hg init
  $ touch a

  $ unset HGUSER
  $ echo "[ui]" >> .hg/hgrc
  $ echo "username= foo" >> .hg/hgrc
  $ echo "          bar1" >> .hg/hgrc

  $ hg ci -Am m
  adding a
  abort: username 'foo\nbar1' contains a newline
  
  [255]
  $ rm .hg/hgrc

  $ HGUSER=`(echo foo; echo bar2)` hg ci -Am m
  adding a
  abort: username 'foo\nbar2' contains a newline
  
  [255]
  $ hg ci -Am m -u "`(echo foo; echo bar3)`"
  adding a
  transaction abort!
  rollback completed
  abort: username 'foo\nbar3' contains a newline!
  [255]