tests/test-username-newline.t

tests: avoid nested quoting on command line for portability

Before this patch, test-revset.t fails on Solaris using ksh as default
"sh", because nested quoting below isn't acceptable for it.

                +-----------------------------+ inner quoting
    "`python -c "print '|'.join(['0:1'] * 500)"`"
    +-------------------------------------------+ outer quoting

This patch does below for portability.

  - omit outer quoting

    This should be safe, because generated string contains no white
    space character.

  - use '+' instead of '|' (for safety)

    '|' has special meaning for many shell, but '+' isn't (at least,
    for ordinary ones).

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