tests/test-issue612.t

revset: add a 'descend' argument to followlines to return descendants

This is useful to follow changes in a block of lines forward in the history
(for instance, when one wants to find out how a function evolved from a point
in history).

We added a 'descend' parameter to followlines(), which defaults to False. If
True, followlines() returns descendants of startrev.

Because context.blockdescendants() does not follow renames, these are not
followed by the revset either, so history will end when a rename occurs (as
can be seen in tests).

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

  $ hg init
  $ 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 (glob)

  $ 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