commit-graph: turn on commit-graph by default

The commit-graph feature has seen a lot of activity in the past
year or so since it was introduced. The feature is a critical
performance enhancement for medium- to large-sized repos, and
does not significantly hurt small repos.

Change the defaults for core.commitGraph and gc.writeCommitGraph
to true so users benefit from this feature by default.

There are several places in the test suite where the environment
variable GIT_TEST_COMMIT_GRAPH is disabled to avoid reading a
commit-graph, if it exists. The config option overrides the
environment, so swap these. Some GIT_TEST_COMMIT_GRAPH assignments
remain, and those are to avoid writing a commit-graph when a new
commit is created.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

4 files changed, 6 insertions, 4 deletions

diff --git a/t/t0410-partial-clone.sh b/t/t0410-partial-clone.sh
index 5bd892f..181ffa4 100755
--- a/t/t0410-partial-clone.sh
+++ b/t/t0410-partial-clone.sh
@@ -234,7 +234,7 @@ test_expect_success 'rev-list stops traversal at missing and promised commit' '
 
 	git -C repo config core.repositoryformatversion 1 &&
 	git -C repo config extensions.partialclone "arbitrary string" &&
-	GIT_TEST_COMMIT_GRAPH=0 git -C repo rev-list --exclude-promisor-objects --objects bar >out &&
+	GIT_TEST_COMMIT_GRAPH=0 git -C repo -c core.commitGraph=false rev-list --exclude-promisor-objects --objects bar >out &&
 	grep $(git -C repo rev-parse bar) out &&
 	! grep $FOO out
 '
diff --git a/t/t5307-pack-missing-commit.sh b/t/t5307-pack-missing-commit.sh
index dacb440..f4338ab 100755
--- a/t/t5307-pack-missing-commit.sh
+++ b/t/t5307-pack-missing-commit.sh
@@ -24,11 +24,11 @@ test_expect_success 'check corruption' '
 '
 
 test_expect_success 'rev-list notices corruption (1)' '
-	test_must_fail env GIT_TEST_COMMIT_GRAPH=0 git rev-list HEAD
+	test_must_fail env GIT_TEST_COMMIT_GRAPH=0 git -c core.commitGraph=false rev-list HEAD
 '
 
 test_expect_success 'rev-list notices corruption (2)' '
-	test_must_fail env GIT_TEST_COMMIT_GRAPH=0 git rev-list --objects HEAD
+	test_must_fail env GIT_TEST_COMMIT_GRAPH=0 git -c core.commitGraph=false rev-list --objects HEAD
 '
 
 test_expect_success 'pack-objects notices corruption' '
diff --git a/t/t5324-split-commit-graph.sh b/t/t5324-split-commit-graph.sh
index 03f45a1..19aa40d 100755
--- a/t/t5324-split-commit-graph.sh
+++ b/t/t5324-split-commit-graph.sh
@@ -8,6 +8,7 @@ GIT_TEST_COMMIT_GRAPH=0
 test_expect_success 'setup repo' '
 	git init &&
 	git config core.commitGraph true &&
+	git config gc.writeCommitGraph false &&
 	infodir=".git/objects/info" &&
 	graphdir="$infodir/commit-graphs" &&
 	test_oid_init
@@ -332,6 +333,7 @@ test_expect_success 'split across alternate where alternate is not split' '
 	git clone --no-hardlinks . alt-split &&
 	(
 		cd alt-split &&
+		rm -f .git/objects/info/commit-graph &&
 		echo "$(pwd)"/../.git/objects >.git/objects/info/alternates &&
 		test_commit 18 &&
 		git commit-graph write --reachable --split &&
diff --git a/t/t6011-rev-list-with-bad-commit.sh b/t/t6011-rev-list-with-bad-commit.sh
index 545b461..bad02cf 100755
--- a/t/t6011-rev-list-with-bad-commit.sh
+++ b/t/t6011-rev-list-with-bad-commit.sh
@@ -42,7 +42,7 @@ test_expect_success 'corrupt second commit object' \
    '
 
 test_expect_success 'rev-list should fail' '
-	test_must_fail env GIT_TEST_COMMIT_GRAPH=0 git rev-list --all > /dev/null
+	test_must_fail env GIT_TEST_COMMIT_GRAPH=0 git -c core.commitGraph=false rev-list --all > /dev/null
 '
 
 test_expect_success 'git repack _MUST_ fail' \