Re: [PATCH v2 5/7] fetch: add --negotiation-require option for negotiation

> From: Derrick Stolee <stolee@gmail.com>
> 
> Add a new --negotiation-require option to 'git fetch', which ensures
> that certain ref tips are always sent as 'have' lines during fetch
> negotiation, regardless of what the negotiation algorithm selects.

> diff --git a/Documentation/fetch-options.adoc b/Documentation/fetch-options.adoc
> index c07b85499f..85ffc5b32b 100644
> --- a/Documentation/fetch-options.adoc
> +++ b/Documentation/fetch-options.adoc
> @@ -73,6 +73,25 @@ See also the `fetch.negotiationAlgorithm` and `push.negotiate`
>  configuration variables documented in linkgit:git-config[1], and the
>  `--negotiate-only` option below.
>  
> +`--negotiation-require=<revision>`::
> +	Ensure that the given ref tip is always sent as a "have" line
> +	during fetch negotiation, regardless of what the negotiation
> +	algorithm selects.  This is useful to guarantee that common
> +	history reachable from specific refs is always considered, even
> +	when `--negotiation-restrict` restricts the set of tips or when
> +	the negotiation algorithm would otherwise skip them.
> ++
> +This option may be specified more than once; if so, each ref is sent
> +unconditionally.
> ++
> +The argument may be an exact ref name (e.g. `refs/heads/release`) or a
> +glob pattern (e.g. `refs/heads/release/{asterisk}`).  The pattern syntax
> +is the same as for `--negotiation-restrict`.
> ++
> +If `--negotiation-restrict` is used, the have set is first restricted by
> +that option and then increased to include the tips specified by
> +`--negotiation-require`.

> diff --git a/fetch-pack.c b/fetch-pack.c
> index baf239adf9..a0029253f1 100644
> --- a/fetch-pack.c
> +++ b/fetch-pack.c
> @@ -474,7 +511,25 @@ static int find_common(struct fetch_negotiator *negotiator,
>  	trace2_region_enter("fetch-pack", "negotiation_v0_v1", the_repository);
>  	flushes = 0;
>  	retval = -1;
> +
> +	/* Send unconditional haves from --negotiation-require */
> +	resolve_negotiation_require(args->negotiation_require,
> +				    &negotiation_require_oids);
> +	if (oidset_size(&negotiation_require_oids)) {
> +		struct oidset_iter iter;
> +		oidset_iter_init(&negotiation_require_oids, &iter);
> +
> +		while ((oid = oidset_iter_next(&iter))) {
> +			packet_buf_write(&req_buf, "have %s\n",
> +					 oid_to_hex(oid));
> +			print_verbose(args, "have %s", oid_to_hex(oid));
> +		}
> +	}