built-in rebase: pick up the ORIG_HEAD fix early

[dscho]

It was reported (a bit belatedly) that there was a regression in v2.21.0 where the built-in rebase would update ORIG_HEAD one times too many, so that it would not point at the pre-rebase state immediately after a rebase completed.

This regression is related (but not identical) to one that was already reported in early January (which was fixed immediately), and for which a regression test had been promised, but which did not materialize until after v2.21.0. Which is too bad, because that re-regression was totally avoidable.

This patch series fixes that problem, and adds a regression test (better late than never, right?) to avoid re-introducing that regression a third time.

This made it (in a slightly different form, see range-diff below) into git.git's next already, via git@f805f820b4b4. Let's take this early, to let Git for Windows' users benefit from the fix as soon as possible.

The range-diff (demonstrating that the RESET_HEAD_RUN_POST_CHECKOUT_HOOK constant requires an adjustment to the RESET_ORIG_HEAD constant):

$ git range-diff cbd29ead92d8~4..cbd29ead92d8 1c5bf602cb63~4..1c5bf602cb63
1:  e6aac8177d02 ! 1:  626431089390 built-in rebase: no need to check out `onto` twice
    @@ -21,7 +21,6 @@
         passing that flag.
     
         Signed-off-by: Johannes Schindelin <[email protected]>
    -    Signed-off-by: Junio C Hamano <[email protected]>
     
      diff --git a/builtin/rebase.c b/builtin/rebase.c
      --- a/builtin/rebase.c
2:  eaf81605b8d1 ! 2:  f13cff1f6457 built-in rebase: use the correct reflog when switching branches
    @@ -5,7 +5,6 @@
         By mistake, we used the reflog intended for ORIG_HEAD.
     
         Signed-off-by: Johannes Schindelin <[email protected]>
    -    Signed-off-by: Junio C Hamano <[email protected]>
     
      diff --git a/builtin/rebase.c b/builtin/rebase.c
      --- a/builtin/rebase.c
3:  c2d96293602b ! 3:  3dfe7f7bb92d built-in rebase: demonstrate that ORIG_HEAD is not set correctly
    @@ -11,7 +11,6 @@
         Reported by Nazri Ramliy.
     
         Signed-off-by: Johannes Schindelin <[email protected]>
    -    Signed-off-by: Junio C Hamano <[email protected]>
     
      diff --git a/t/t3400-rebase.sh b/t/t3400-rebase.sh
      --- a/t/t3400-rebase.sh
4:  cbd29ead92d8 ! 4:  1c5bf602cb63 built-in rebase: set ORIG_HEAD just once, before the rebase
    @@ -16,22 +16,21 @@
         So let's do that.
     
         Signed-off-by: Johannes Schindelin <[email protected]>
    -    Signed-off-by: Junio C Hamano <[email protected]>
     
      diff --git a/builtin/rebase.c b/builtin/rebase.c
      --- a/builtin/rebase.c
      +++ b/builtin/rebase.c
     @@
    - #define RESET_HEAD_DETACH (1<<0)
      #define RESET_HEAD_HARD (1<<1)
    - #define RESET_HEAD_REFS_ONLY (1<<2)
    -+#define RESET_ORIG_HEAD (1<<3)
    + #define RESET_HEAD_RUN_POST_CHECKOUT_HOOK (1<<2)
    + #define RESET_HEAD_REFS_ONLY (1<<3)
    ++#define RESET_ORIG_HEAD (1<<4)
      
      static int reset_head(struct object_id *oid, const char *action,
      		      const char *switch_to_branch, unsigned flags,
     @@
    - 	unsigned detach_head = flags & RESET_HEAD_DETACH;
      	unsigned reset_hard = flags & RESET_HEAD_HARD;
    + 	unsigned run_hook = flags & RESET_HEAD_RUN_POST_CHECKOUT_HOOK;
      	unsigned refs_only = flags & RESET_HEAD_REFS_ONLY;
     +	unsigned update_orig_head = flags & RESET_ORIG_HEAD;
      	struct object_id head_oid;
    @@ -75,8 +74,10 @@
      	strbuf_addf(&msg, "%s: checkout %s",
      		    getenv(GIT_REFLOG_ACTION_ENVIRONMENT), options.onto_name);
      	if (reset_head(&options.onto->object.oid, "checkout", NULL,
    --		       RESET_HEAD_DETACH, NULL, msg.buf))
    -+		       RESET_HEAD_DETACH | RESET_ORIG_HEAD, NULL, msg.buf))
    +-		       RESET_HEAD_DETACH | RESET_HEAD_RUN_POST_CHECKOUT_HOOK,
    +-		       NULL, msg.buf))
    ++		       RESET_HEAD_DETACH | RESET_HEAD_RUN_POST_CHECKOUT_HOOK |
    ++		       RESET_ORIG_HEAD, NULL, msg.buf))
      		die(_("Could not detach HEAD"));
      	strbuf_release(&msg);
      

[orgads]

👍

[dscho]

@orgads thank you for reviewing!