tests/test-issue612.t

rhg: in path_encode, split Dest into VecDest and MeasureDest

Two separate types make the write semantics easier to understand
because we can consider the two sinks separately.

Having two independent compiled functions for size measurement
and for actual encoding seems likely to improve performance, too.
(and maybe we should get rid of measurement altogether)

Getting rid of [Dest] also removes the ugly option rewrapping
code, which is good.

https://bz.mercurial-scm.org/612

  $ hg init repo
  $ cd repo
  $ mkdir src
  $ echo a > src/a.c
  $ hg ci -Ama
  adding src/a.c

  $ hg mv src source
  moving src/a.c to source/a.c

  $ hg ci -Ammove

  $ hg co -C 0
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved

  $ echo new > src/a.c
  $ echo compiled > src/a.o
  $ hg ci -mupdate
  created new head

  $ hg status
  ? src/a.o

  $ hg merge
  merging src/a.c and source/a.c to source/a.c
  0 files updated, 1 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)

  $ hg status
  M source/a.c
  R src/a.c
  ? src/a.o