repo-settings: rename the traditional default fetch.negotiationAlgorithm

Give the traditional default fetch.negotiationAlgorithm the name
'consecutive'.  Also allow a choice of 'default' to have Git decide
between the choices (currently, picking 'skipping' if
feature.experimental is true and 'consecutive' otherwise).  Update the
documentation accordingly.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/config/fetch.txt

@@ -56,18 +56,19 @@ fetch.output::
 	OUTPUT in linkgit:git-fetch[1] for detail.
 
 fetch.negotiationAlgorithm::
-	Control how information about the commits in the local repository is
+	Control how information about the commits in the local repository
-	sent when negotiating the contents of the packfile to be sent by the
+	is sent when negotiating the contents of the packfile to be sent by
-	server. Set to "skipping" to use an algorithm that skips commits in an
+	the server.  Set to "consecutive" to use an algorithm that walks
-	effort to converge faster, but may result in a larger-than-necessary
+	over consecutive commits checking each one.  Set to "skipping" to
-	packfile; or set to "noop" to not send any information at all, which
+	use an algorithm that skips commits in an effort to converge
-	will almost certainly result in a larger-than-necessary packfile, but
+	faster, but may result in a larger-than-necessary packfile; or set
-	will skip the negotiation step.
+	to "noop" to not send any information at all, which will almost
-	The default is "default" which instructs Git to use the default algorithm
+	certainly result in a larger-than-necessary packfile, but will skip
-	that never skips commits (unless the server has acknowledged it or one
+	the negotiation step.  Set to "default" to override settings made
-	of its descendants). If `feature.experimental` is enabled, then this
+	previously and use the default behaviour.  The default is normally
-	setting defaults to "skipping".
+	"consecutive", but if `feature.experimental` is true, then the
-	Unknown values will cause 'git fetch' to error out.
+	default is "skipping".  Unknown values will cause 'git fetch' to
+	error out.
 +
 See also the `--negotiate-only` and `--negotiation-tip` options to
 linkgit:git-fetch[1].

fetch-negotiator.c

@@ -18,7 +18,7 @@ void fetch_negotiator_init(struct repository *r,
 		noop_negotiator_init(negotiator);
 		return;
 
-	case FETCH_NEGOTIATION_DEFAULT:
+	case FETCH_NEGOTIATION_CONSECUTIVE:
 		default_negotiator_init(negotiator);
 		return;
 	}

repo-settings.c

@@ -23,7 +23,7 @@ void prepare_repo_settings(struct repository *r)
 	/* Defaults */
 	r->settings.index_version = -1;
 	r->settings.core_untracked_cache = UNTRACKED_CACHE_KEEP;
-	r->settings.fetch_negotiation_algorithm = FETCH_NEGOTIATION_DEFAULT;
+	r->settings.fetch_negotiation_algorithm = FETCH_NEGOTIATION_CONSECUTIVE;
 
 	/* Booleans config or default, cascades to other settings */
 	repo_cfg_bool(r, "feature.manyfiles", &manyfiles, 0);
@@ -78,12 +78,15 @@ void prepare_repo_settings(struct repository *r)
 	}
 
 	if (!repo_config_get_string(r, "fetch.negotiationalgorithm", &strval)) {
+		int fetch_default = r->settings.fetch_negotiation_algorithm;
 		if (!strcasecmp(strval, "skipping"))
 			r->settings.fetch_negotiation_algorithm = FETCH_NEGOTIATION_SKIPPING;
 		else if (!strcasecmp(strval, "noop"))
 			r->settings.fetch_negotiation_algorithm = FETCH_NEGOTIATION_NOOP;
+		else if (!strcasecmp(strval, "consecutive"))
+			r->settings.fetch_negotiation_algorithm = FETCH_NEGOTIATION_CONSECUTIVE;
 		else if (!strcasecmp(strval, "default"))
-			r->settings.fetch_negotiation_algorithm = FETCH_NEGOTIATION_DEFAULT;
+			r->settings.fetch_negotiation_algorithm = fetch_default;
 		else
 			die("unknown fetch negotiation algorithm '%s'", strval);
 	}

repository.h

@@ -19,7 +19,7 @@ enum untracked_cache_setting {
 };
 
 enum fetch_negotiation_setting {
-	FETCH_NEGOTIATION_DEFAULT,
+	FETCH_NEGOTIATION_CONSECUTIVE,
 	FETCH_NEGOTIATION_SKIPPING,
 	FETCH_NEGOTIATION_NOOP,
 };

t/t5500-fetch-pack.sh

@@ -968,7 +968,7 @@ test_expect_success 'use ref advertisement to prune "have" lines sent' '
 test_expect_success 'same as last but with config overrides' '
 	test_negotiation_algorithm_default \
 		-c feature.experimental=true \
-		-c fetch.negotiationAlgorithm=default
+		-c fetch.negotiationAlgorithm=consecutive
 '
 
 test_expect_success 'ensure bogus fetch.negotiationAlgorithm yields error' '