tests/test-issue1175.t

extensions: move the "import" logic out from "load"

The "load" method does too many things: on-demand import and check version.
This patch moves the import logic out from "load" so it could be wrapped to
change the import behavior, for example, chg will use it to pre-import
extensions.

https://bz.mercurial-scm.org/1175

  $ hg init
  $ touch a
  $ hg ci -Am0
  adding a

  $ hg mv a a1
  $ hg ci -m1

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

  $ hg mv a a2
  $ hg up
  note: possible conflict - a was renamed multiple times to:
   a2
   a1
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ hg ci -m2

  $ touch a
  $ hg ci -Am3
  adding a

  $ hg mv a b
  $ hg ci -Am4 a

  $ hg ci --debug --traceback -Am5 b
  committing files:
  b
  warning: can't find ancestor for 'b' copied from 'a'!
  committing manifest
  committing changelog
  committed changeset 5:83a687e8a97c80992ba385bbfd766be181bfb1d1

  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  4 files, 6 changesets, 4 total revisions

  $ hg export --git tip
  # HG changeset patch
  # User test
  # Date 0 0
  #      Thu Jan 01 00:00:00 1970 +0000
  # Node ID 83a687e8a97c80992ba385bbfd766be181bfb1d1
  # Parent  1d1625283f71954f21d14c3d44d0ad3c019c597f
  5
  
  diff --git a/b b/b
  new file mode 100644

https://bz.mercurial-scm.org/show_bug.cgi?id=4476

  $ hg init foo
  $ cd foo
  $ touch a && hg ci -Aqm a
  $ hg mv a b
  $ echo b1 >> b
  $ hg ci -Aqm b1
  $ hg up 0
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ hg mv a b
  $ echo b2 >> b
  $ hg ci -Aqm b2
  $ hg graft 1
  grafting 1:5974126fad84 "b1"
  merging b
  warning: conflicts while merging b! (edit, then use 'hg resolve --mark')
  abort: unresolved conflicts, can't continue
  (use 'hg resolve' and 'hg graft --continue')
  [255]
  $ echo a > b
  $ echo b3 >> b
  $ hg resolve --mark b
  (no more unresolved files)
  continue: hg graft --continue
  $ hg graft --continue
  grafting 1:5974126fad84 "b1"
  warning: can't find ancestor for 'b' copied from 'a'!
  $ hg log -f b -T 'changeset:   {rev}:{node|short}\nsummary:     {desc}\n\n'
  changeset:   3:376d30ccffc0
  summary:     b1
  
  changeset:   2:416baaa2e5e4
  summary:     b2
  
  changeset:   0:3903775176ed
  summary:     a