Re: [PATCH v2 5/5] Revert "repository: pre-initialize hash algo pointer"

This reverts commit e26f7f19b6c7485f04234946a59ab8f4fd21d6d1. The root
problem, git clone not setting up the_hash_algo, has been fixed in the
previous patch.

Since this is a dangerous move and could potentially break stuff after
release (and leads to workaround like the reverted commit), the
workaround technically remains, but is hidden behind a new environment
variable GIT_HASH_FIXUP. This should let the users continue to use git
while we fix the problem. This variable can be deleted after one or two
releases.

Signed-off-by: Nguyễn Thái Ngọc Duy <redacted>
---
 common-main.c                    | 10 ++++++++++
 repository.c                     |  2 +-
 t/helper/test-dump-split-index.c |  2 ++
 3 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/common-main.c b/common-main.c
index 6a689007e7..fbfa98c3b8 100644
--- a/common-main.c
+++ b/common-main.c

@@ -1,6 +1,7 @@
 #include "cache.h"
 #include "exec_cmd.h"
 #include "attr.h"
+#include "repository.h"
 
 /*
  * Many parts of Git have subprograms communicate via pipe, expect the

@@ -40,5 +41,14 @@ int main(int argc, const char **argv)
 
 	restore_sigpipe_to_default();
 
+	/*
+	 * Temporary recovery measure while hashing code is being
+	 * refactored. This variable should be gone after everybody
+	 * has used the_hash_algo in one or two releases and nobody
+	 * complains anything.
+	 */
+	if (getenv("GIT_HASH_FIXUP"))
+		repo_set_hash_algo(the_repository, GIT_HASH_SHA1);
+
 	return cmd_main(argc, argv);
 }

diff --git a/repository.c b/repository.c
index 4ffbe9bc94..0d715f4fdb 100644
--- a/repository.c
+++ b/repository.c

@@ -5,7 +5,7 @@
 
 /* The main repository */
 static struct repository the_repo = {
-	NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, &the_index, &hash_algos[GIT_HASH_SHA1], 0, 0
+	NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, &the_index, NULL, 0, 0