git-rebase.txt: add another hook to the hooks section, and explain more

For more discussion about these hooks, their history relative to rebase,
and logical consistency between different types of operations, see
  https://lore.kernel.org/git/CABPp-BG0bFKUage5cN_2yr2DkmS04W2Z9Pg5WcROqHznV3XBdw@mail.gmail.com/
and the links to some threads referenced therein.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 11 insertions, 3 deletions

diff --git a/Documentation/git-rebase.txt b/Documentation/git-rebase.txt
index f7a6033..5a756b5 100644
--- a/Documentation/git-rebase.txt
+++ b/Documentation/git-rebase.txt
@@ -684,9 +684,17 @@ Hooks
 ~~~~~
 
 The apply backend has not traditionally called the post-commit hook,
-while the merge backend has.  However, this was by accident of
-implementation rather than by design.  Both backends should have the
-same behavior, though it is not clear which one is correct.
+while the merge backend has.  Both have called the post-checkout hook,
+though the merge backend has squelched its output.  Further, both
+backends only call the post-checkout hook with the starting point
+commit of the rebase, not the intermediate commits nor the final
+commit.  In each case, the calling of these hooks was by accident of
+implementation rather than by design (both backends were originally
+implemented as shell scripts and happened to invoke other commands
+like 'git checkout' or 'git commit' that would call the hooks).  Both
+backends should have the same behavior, though it is not entirely
+clear which, if any, is correct.  We will likely make rebase stop
+calling either of these hooks in the future.
 
 Interruptability
 ~~~~~~~~~~~~~~~~