tests/test-basic.t

run-tests: set a default largefiles usercache in the default hgrc file

This fixes a test failure introduced in 4be754832829 on Windows and OS X, where
the cached largefile wasn't being deleted because the named .cache directory
didn't exist.  It only existed on Linux because the test suite sets $HOME to the
directory of the test being run, and Linux uses $HOME/.cache by default.

Most of the other largefiles tests explicitly set this value at the top of their
scripts, but test-largefiles-update.t didn't pick that up when it was created.
Those scripts that do set a value will override this.

We could just set the parameter in the test-largefiles-update.t script, but
there are a few other non obvious tests that exercise largefiles too.  These
largefiles end up being cached in the user's real cache, so proper hygiene
dictates that this not be left to each individual test script.

Create a repository:

  $ hg config
  defaults.backout=-d "0 0"
  defaults.commit=-d "0 0"
  defaults.shelve=--date "0 0"
  defaults.tag=-d "0 0"
  largefiles.usercache=$TESTTMP/.cache/largefiles (glob)
  ui.slash=True
  ui.interactive=False
  ui.mergemarkers=detailed
  ui.promptecho=True
  $ hg init t
  $ cd t

Make a changeset:

  $ echo a > a
  $ hg add a
  $ hg commit -m test

This command is ancient:

  $ hg history
  changeset:   0:acb14030fe0a
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     test
  

Verify that updating to revision 0 via commands.update() works properly

  $ cat <<EOF > update_to_rev0.py
  > from mercurial import ui, hg, commands
  > myui = ui.ui()
  > repo = hg.repository(myui, path='.')
  > commands.update(myui, repo, rev=0)
  > EOF
  $ hg up null
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ python ./update_to_rev0.py
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg identify -n
  0


Poke around at hashes:

  $ hg manifest --debug
  b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3 644   a

  $ hg cat a
  a

Verify should succeed:

  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  1 files, 1 changesets, 1 total revisions

At the end...

  $ cd ..