tests/test-username-newline.t

templates/filters: extracting the user portion of an email address

Currently, the 'user' filter is using util.shortuser(text) (which clearly
doesn't extract only the user portion of an email address, even though the
help text says it does).

The new 'emailuser' filter uses the new util.emailuser(text) function which,
instead, does exactly that.

The help text on the 'user' filter has been modified accordingly.

  $ 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]