tests/test-diff-subdir.t

simplemerge: take arguments as annotated context objects

The labels we put in conflict markers are formatted so the part before
the ':' (typically says things like "local") is padded so the ':' is
aligned among the labels. That means that if you specify a long label
for "base" but the conflict marker style is "merge" (i.e. 2-way), the
other two will have unwanted padding. We often don't specify a label
for the base, so we don't notice the problem (and it may very well be
that it didn't exist before my D11972).

I think the best fix is to pass the labels along with the context
objects, so the low-level code that switches on the marker style to
use (i.e. `simplemerge`) can do the formatting. This patch starts
doing that by passing a fully-formatted label to `simplemerge`. A
coming patch will move the formatting to `simplemerge`.

Differential Revision: https://phab.mercurial-scm.org/D12013

  $ hg init

  $ mkdir alpha
  $ touch alpha/one
  $ mkdir beta
  $ touch beta/two

  $ hg add alpha/one beta/two
  $ hg ci -m "start"

  $ echo 1 > alpha/one
  $ echo 2 > beta/two

everything

  $ hg diff --nodates
  diff -r 7d5ef1aea329 alpha/one
  --- a/alpha/one
  +++ b/alpha/one
  @@ -0,0 +1,1 @@
  +1
  diff -r 7d5ef1aea329 beta/two
  --- a/beta/two
  +++ b/beta/two
  @@ -0,0 +1,1 @@
  +2

beta only

  $ hg diff --nodates beta
  diff -r 7d5ef1aea329 beta/two
  --- a/beta/two
  +++ b/beta/two
  @@ -0,0 +1,1 @@
  +2

inside beta

  $ cd beta
  $ hg diff --nodates .
  diff -r 7d5ef1aea329 beta/two
  --- a/beta/two
  +++ b/beta/two
  @@ -0,0 +1,1 @@
  +2

relative to beta

  $ cd ..
  $ hg diff --nodates --root beta
  diff -r 7d5ef1aea329 two
  --- a/two
  +++ b/two
  @@ -0,0 +1,1 @@
  +2

inside beta

  $ cd beta
  $ hg diff --nodates --root .
  diff -r 7d5ef1aea329 two
  --- a/two
  +++ b/two
  @@ -0,0 +1,1 @@
  +2

  $ cd ..