Update NEWS.
send a packfile if there is an update/create cmd

Add check for update/create commands (non delete commands)
when deciding to send a packfile on send_pack.

According to the pack protocol for receive-pack at

https://www.kernel.org/pub/software/scm/git/docs/v1.7.1/technical/pack-protocol.txt

A pack-file MUST be sent if either create or update command is used,
even if the server already has all the necessary objects.  In this
case the client MUST send an empty pack-file.   The only time this
is likely to happen is if the client is creating
a new branch or a tag that points to an existing obj-id.

Signed-off-by: Jelmer Vernooij <jelmer@samba.org>
Remove delete commands when no delete=refs

Add check for no 'delete-refs' from server and remove commands.
Additionally, report as if these commands failed.

According to the pack protocol for receive-pack at

https://www.kernel.org/pub/software/scm/git/docs/v1.7.1/technical/pack-protocol.txt

If the receiving end does not support delete-refs, the sending end MUST
NOT ask for delete command.

Signed-off-by: Jelmer Vernooij <jelmer@samba.org>
Update NEWS.
Add SSHVendor abstraction class.
Fix capability negotiation when fetching packs over HTTP.
Fix run_git_or_fail to let stderr be overridden.

GitHTTPServer relies on stderr being sent to nowhere, but
run_git_or_fail always sent it to stdout, causing non-side-band clients
to fail.
Merge branch 'http-fetch-capa' of git://github.com/wgrant/dulwich

Conflicts:
	NEWS
Add Repo.get_description method.
Support thin packs in Pack.iterobjects(), Pack.get_raw().
Pack's constructor now takes resolve_ext_ref.
Update NEWS.
Add add_pack and add_thin_pack methods to MemoryObjectStore.

Closes #97.

Signed-off-by: Jelmer Vernooij <jelmer@samba.org>

Conflicts:
	NEWS
Fix SSHGitClient regressions