Re: [PATCH v5 2/4] t3427: accelerate this test by using fast-export and fast-import

From: Junio C Hamano <gitster@pobox.com>
Date: Sep 3, 2019, 21:26 UTC
Message-ID: <xmqqsgpdrs01.fsf@gitster-ct.c.googlers.com>
In-Reply-To: <20190903185524.13467-3-newren@gmail.com>

Elijah Newren <newren@gmail.com> writes:

Show 5 quoted lines

> +extract_files_subtree () {
> +	git fast-export --no-data HEAD -- files_subtree/ |
> +		sed -e "s%\([0-9a-f]\{40\} \)files_subtree/%\1%" |
> +		git fast-import --force --quiet
> +}

Clever, if a bit filthy ;-).  We expect to see something like

	M 100644 dead...beef files_subtree/bar
	M 100755 c0f.....fee files_subtree/foo

in the --no-data output, and the assumption here is that 40-hex followed by " files_subtree/" would never appear anywhere in the stream other than these tree dump, so the sed script can rewrite the above to

	M 100644 dead...beef bar
	M 100755 c0f.....fee foo

by getting rid of the leading directory name (plus the slash at the end).

Thanks.