tests/test-mactext.t

bundle2: extract a _payloadchunks method for part

We are preparing streaming capability for part. So the generation of payload
chunk will becomes more complex. We extract this part in its own function before
any changes.

  $ cat > unix2mac.py <<EOF
  > import sys
  > 
  > for path in sys.argv[1:]:
  >     data = file(path, 'rb').read()
  >     data = data.replace('\n', '\r')
  >     file(path, 'wb').write(data)
  > EOF
  $ cat > print.py <<EOF
  > import sys
  > print(sys.stdin.read().replace('\n', '<LF>').replace('\r', '<CR>').replace('\0', '<NUL>'))
  > EOF
  $ hg init
  $ echo '[hooks]' >> .hg/hgrc
  $ echo 'pretxncommit.cr = python:hgext.win32text.forbidcr' >> .hg/hgrc
  $ echo 'pretxnchangegroup.cr = python:hgext.win32text.forbidcr' >> .hg/hgrc
  $ cat .hg/hgrc
  [hooks]
  pretxncommit.cr = python:hgext.win32text.forbidcr
  pretxnchangegroup.cr = python:hgext.win32text.forbidcr

  $ echo hello > f
  $ hg add f
  $ hg ci -m 1

  $ python unix2mac.py f
  $ hg ci -m 2
  attempt to commit or push text file(s) using CR line endings
  in dea860dc51ec: f
  transaction abort!
  rollback completed
  abort: pretxncommit.cr hook failed
  [255]
  $ hg cat f | python print.py
  hello<LF>
  $ cat f | python print.py
  hello<CR>