There are currently two hooks that have hardcoded 40 zeros as the null
OID and, thus, are not hash-agnostic. Rewrite these to use the newly
introduced `git rev-parse --null-oid` so that they become hash-agnostic.

Denton Liu (4):
  hooks--pre-push.sample: prefer $() for command substitution
  builtin/rev-parse: learn --null-oid
  hooks--pre-push.sample: use hash-agnostic null OID
  hooks--update.sample: use hash-agnostic null OID

 Documentation/git-rev-parse.txt  | 4 ++++
 builtin/rev-parse.c              | 4 ++++
 t/t1500-rev-parse.sh             | 6 ++++++
 templates/hooks--pre-push.sample | 8 ++++----
 templates/hooks--update.sample   | 2 +-
 5 files changed, 19 insertions(+), 5 deletions(-)

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2.28.0.618.gf4bc123cb7