Documentation/config/extensions.txt

extensions.objectFormat::
	Specify the hash algorithm to use.  The acceptable values are `sha1` and
	`sha256`.  If not specified, `sha1` is assumed.  It is an error to specify
	this key unless `core.repositoryFormatVersion` is 1.
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Note that this setting should only be set by linkgit:git-init[1] or
linkgit:git-clone[1].  Trying to change it after initialization will not
work and will produce hard-to-diagnose issues.

extensions.refStorage::
	Specify the ref storage format to use. The acceptable values are:
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include::../ref-storage-format.txt[]
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It is an error to specify this key unless `core.repositoryFormatVersion` is 1.
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Note that this setting should only be set by linkgit:git-init[1] or
linkgit:git-clone[1]. Trying to change it after initialization will not
work and will produce hard-to-diagnose issues.

extensions.worktreeConfig::
	If enabled, then worktrees will load config settings from the
	`$GIT_DIR/config.worktree` file in addition to the
	`$GIT_COMMON_DIR/config` file. Note that `$GIT_COMMON_DIR` and
	`$GIT_DIR` are the same for the main working tree, while other
	working trees have `$GIT_DIR` equal to
	`$GIT_COMMON_DIR/worktrees/<id>/`. The settings in the
	`config.worktree` file will override settings from any other
	config files.
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When enabling `extensions.worktreeConfig`, you must be careful to move
certain values from the common config file to the main working tree's
`config.worktree` file, if present:
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* `core.worktree` must be moved from `$GIT_COMMON_DIR/config` to
  `$GIT_COMMON_DIR/config.worktree`.
* If `core.bare` is true, then it must be moved from `$GIT_COMMON_DIR/config`
  to `$GIT_COMMON_DIR/config.worktree`.
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It may also be beneficial to adjust the locations of `core.sparseCheckout`
and `core.sparseCheckoutCone` depending on your desire for customizable
sparse-checkout settings for each worktree. By default, the `git
sparse-checkout` builtin enables `extensions.worktreeConfig`, assigns
these config values on a per-worktree basis, and uses the
`$GIT_DIR/info/sparse-checkout` file to specify the sparsity for each
worktree independently. See linkgit:git-sparse-checkout[1] for more
details.
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For historical reasons, `extensions.worktreeConfig` is respected
regardless of the `core.repositoryFormatVersion` setting.