[PATCH 22/30] packed-backend: create GIT_TEST_PACKED_REFS_VERSION

["Derrick Stolee via GitGitGadget" <gitgitgadget@gmail.com>]

From: Derrick Stolee <derrickstolee@github.com>

When set, this will create a default value for the packed-refs file
version on writes. When set to "2", it will automatically add the
"packed-v2" value to extensions.refFormat.

Not all tests pass with GIT_TEST_PACKED_REFS_VERSION=2 because they care
specifically about the content of the packed-refs file. These tests will
be updated in following changes.

To start, though, disable the GIT_TEST_PACKED_REFS_VERSION environment
variable in t3212-ref-formats.sh, since that script already tests both
versions, including upgrade scenarios.

Signed-off-by: Derrick Stolee <derrickstolee@github.com>
---
 refs/packed-backend.c  | 3 ++-
 setup.c                | 5 ++++-
 t/t3212-ref-formats.sh | 3 +++
 3 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/refs/packed-backend.c b/refs/packed-backend.c
index ae904de9014..e84f669c42e 100644
--- a/refs/packed-backend.c
+++ b/refs/packed-backend.c
@@ -807,7 +807,8 @@ static int write_with_updates(struct packed_ref_store *refs,
 	}
 	strbuf_release(&sb);
 
-	if (git_config_get_int("refs.packedrefsversion", &version)) {
+	if (!(version = git_env_ulong("GIT_TEST_PACKED_REFS_VERSION", 0)) &&
+	    git_config_get_int("refs.packedrefsversion", &version)) {
 		/*
 		 * Set the default depending on the current extension
 		 * list. Default to version 1 if available, but allow a
diff --git a/setup.c b/setup.c
index 72bfa289ade..a4525732fe9 100644
--- a/setup.c
+++ b/setup.c
@@ -732,8 +732,11 @@ int read_repository_format(struct repository_format *format, const char *path)
 		clear_repository_format(format);
 
 	/* Set default ref_format if no extensions.refFormat exists. */
-	if (!format->ref_format_count)
+	if (!format->ref_format_count) {
 		format->ref_format = REF_FORMAT_FILES | REF_FORMAT_PACKED;
+		if (git_env_ulong("GIT_TEST_PACKED_REFS_VERSION", 0) == 2)
+			format->ref_format |= REF_FORMAT_PACKED_V2;
+	}
 
 	return format->version;
 }
diff --git a/t/t3212-ref-formats.sh b/t/t3212-ref-formats.sh
index 571ba518ef1..5583f16db41 100755
--- a/t/t3212-ref-formats.sh
+++ b/t/t3212-ref-formats.sh
@@ -2,6 +2,9 @@
 
 test_description='test across ref formats'
 
+GIT_TEST_PACKED_REFS_VERSION=0
+export GIT_TEST_PACKED_REFS_VERSION
+
 . ./test-lib.sh
 
 test_expect_success 'extensions.refFormat requires core.repositoryFormatVersion=1' '
-- 
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