tests/test-username-newline.t

addremove: use uipathfn instead of m.rel() for recorded similatity message

When no path arguments are given to addremove, it generally prints
absolute paths. However, before this patch, we would always print the
"recording removal of foo as rename to bar (78% similar)" message with
relative paths.

Differential Revision: https://phab.mercurial-scm.org/D5913

  $ 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]