[PATCHv9 0/4] ref namespaces

[Josh Triplett <josh@joshtriplett.org>]

This series adds support for dividing the refs of a single repository
into multiple namespaces, each of which can have its own branches, tags,
and HEAD. Git can expose each namespace as an independent repository to
pull from and push to, while sharing the object store, and exposing all
the refs to operations such as git-gc.

Storing multiple repositories as namespaces of a single repository
avoids storing duplicate copies of the same objects, such as when
storing multiple branches of the same source.  The alternates mechanism
provides similar support for avoiding duplicates, but alternates do not
prevent duplication between new objects added to the repositories
without ongoing maintenance, while namespaces do.

The first patch improves the prefix handling in the ref iteration
functions, making it possible for us to implement
for_each_namespaced_ref later. The next two patches implement and then
use infrastructure for tracking the current namespace and iterating over
the refs in that namespace. The last patch adds general documentation
for namespaces, and specific references from the documentation on
receive-pack, upload-pack, http-backend, and git.

v9: Fix a regression in alternatives handling, introduced in patch 3:
the ref filtering also filtered out the ".have" refs added by
receive-pack to announce refs provided by alternates.  In the process of
fixing this, also announce any refs outside the current namespace as
".have" refs, to allow the client to use those for minimal transfer as
well.  Also, remove patch attribution in commit messages as requested by
Junio C Hamano.  Finally, attempt to change the commit message style to
more closely match Git's preferred style; further feedback welcome on
any other desired changes to the commit message style.

Josh Triplett (4):
  Fix prefix handling in ref iteration functions
  ref namespaces: infrastructure
  ref namespaces: Support remote repositories via upload-pack and
    receive-pack
  ref namespaces: documentation

 Documentation/Makefile                 |    2 +-
 Documentation/git-http-backend.txt     |    8 +++
 Documentation/git-receive-pack.txt     |    2 +-
 Documentation/git-upload-pack.txt      |    4 ++
 Documentation/git.txt                  |   13 +++++-
 Documentation/gitnamespaces.txt        |   75 ++++++++++++++++++++++++++++++++
 builtin/receive-pack.c                 |   37 +++++++++++++---
 cache.h                                |    3 +
 contrib/completion/git-completion.bash |    3 +-
 environment.c                          |   41 +++++++++++++++++
 git.c                                  |   18 +++++++-
 refs.c                                 |   33 ++++++++++++--
 refs.h                                 |    3 +
 upload-pack.c                          |   15 +++---
 14 files changed, 233 insertions(+), 24 deletions(-)
 create mode 100644 Documentation/gitnamespaces.txt

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1.7.5.4