tests/test-unrelated-pull.t

localrepo: make supported features manageable in each repositories individually

Before this patch, all localrepositories support same features,
because supported features are managed by the class variable
"supported" of "localrepository".

For example, "largefiles" feature provided by largefiles extension is
recognized as supported, by adding the feature name to "supported" of
"localrepository".

So, commands handling multiple repositories at a time like below
misunderstand that such features are supported also in repositories
not enabling corresponded extensions:

  - clone/pull from or push to localhost
  - recursive execution in subrepo tree

"reposetup()" can't be used to fix this problem, because it is invoked
after checking whether supported features satisfy ones required in the
target repository.

So, this patch adds the set object named as "featuresetupfuncs" to
"localrepository" to manage hook functions to setup supported features
of each repositories.

If any functions are added to "featuresetupfuncs", they are invoked,
and information about supported features is managed in each
repositories individually.

This patch also adds checking below:

  - pull from localhost: whether features supported in the local(= dst)
    repository satisfies ones required in the remote(= src)

  - push to localhost: whether features supported in the remote(= dst)
    repository satisfies ones required in the local(= src)

Managing supported features by the class variable means that there is
no difference of supported features between each instances of
"localrepository" in the same Python process, so such checking is not
needed before this patch.

Even with this patch, if intermediate bundlefile is used as pulling
source, pulling indirectly from the remote repository, which requires
features more than ones supported in the local, can't be prevented,
because bundlefile has no information about "required features" in it.

  $ hg init a
  $ cd a
  $ echo 123 > a
  $ hg add a
  $ hg commit -m "a" -u a

  $ cd ..
  $ hg init b
  $ cd b
  $ echo 321 > b
  $ hg add b
  $ hg commit -m "b" -u b

  $ hg pull ../a
  pulling from ../a
  searching for changes
  abort: repository is unrelated
  [255]

  $ hg pull -f ../a
  pulling from ../a
  searching for changes
  warning: repository is unrelated
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files (+1 heads)
  (run 'hg heads' to see heads, 'hg merge' to merge)

  $ hg heads
  changeset:   1:9a79c33a9db3
  tag:         tip
  parent:      -1:000000000000
  user:        a
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     a
  
  changeset:   0:01f8062b2de5
  user:        b
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     b
  

  $ cd ..