[PATCH v3 23/24] introduce GIT_INDEX_VERSION environment variable

[Thomas Gummerer <t.gummerer@gmail.com>]

Respect a GIT_INDEX_VERSION environment variable, when a new index is
initialized.  Setting the environment variable will not cause existing
index files to be converted to another format for additional safety.

Signed-off-by: Thomas Gummerer <t.gummerer@gmail.com>
---
 read-cache.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/read-cache.c b/read-cache.c
index 1d9b615..f820d8a 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -1235,8 +1235,13 @@ static struct cache_entry *refresh_cache_entry(struct cache_entry *ce, int reall
 void initialize_index(struct index_state *istate, int version)
 {
 	istate->initialized = 1;
-	if (!version)
-		version = INDEX_FORMAT_DEFAULT;
+	if (!version) {
+		char *envversion = getenv("GIT_INDEX_VERSION");
+		if (!envversion)
+			version = INDEX_FORMAT_DEFAULT;
+		else
+			version = atoi(envversion);
+	}
 	istate->version = version;
 	set_istate_ops(istate);
 }
-- 
1.8.3.4.1231.g9fbf354.dirty