tests/test-merge8.t

log: add a "graphwidth" template variable

Wrapping text in templates for 'hg log --graph' can't be done very well,
because the template doesn't know how wide the graph drawing is. The edge
drawing function needs to know the number of lines in the template output, so
we need to also determine how wide that drawing would be before we call the
edgefn or evaluate the template.

This patch makes edgefn compute the graph width and pass it into the template
so that we can do something like this:

COLUMNS=10 hg log --graph --template "{fill(desc, termwidth - graphwidth)}"
@  a a a a
|  a a a a
|  a a a a
o    a a a
|\   a a a
| |  a a a
| |  a a a

Using extensions to do this would be relatively complicated due to a lack of
hooks in this area of the code.

In the future it may make sense to have a more generic "textwidth" that tells
you how many columns you can expect to fill without causing the terminal to
wrap your output. I'm not sure there are other situations to motivate this yet,
or if it is entirely feasible.

Differential Revision: https://phab.mercurial-scm.org/D360

Test for changeset ba7c74081861
(update dirstate correctly for non-branchmerge updates)
  $ hg init a
  $ cd a
  $ echo a > a
  $ hg add a
  $ hg commit -m a
  $ cd ..
  $ hg clone a b
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd a
  $ hg mv a b
  $ hg commit -m move
  $ echo b >> b
  $ hg commit -m b
  $ cd ../b
  $ hg pull ../a
  pulling from ../a
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 2 changes to 1 files
  (run 'hg update' to get a working copy)
  $ hg update
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved

  $ cd ..