Re: [PATCH v2 0/2] repack -ad: fix after `fetch --prune` in a shallow repository

[Jeff King <peff@peff.net>]

On Tue, Jul 17, 2018 at 06:51:39AM -0700, Johannes Schindelin via GitGitGadget wrote:

> Under certain circumstances, commits that were reachable can be made
> unreachable, e.g. via `git fetch --prune`. These commits might have
> been packed already, in which case `git repack -adlf` will just drop
> them without giving them the usual grace period before an eventual
> `git prune` (via `git gc`) prunes them.
> 
> This is a problem when the `shallow` file still lists them, which is
> the reason why `git prune` edits that file. And with the proposed
> changes, `git repack -ad` will now do the same.
> 
> Reported by Alejandro Pauly.
> 
> Changes since v1:
> 
> - Also trigger `prune_shallow()` when `--unpack-unreachable=<approxidate>` was passed to `git repack`.
> - No need to trigger `prune_shallow()` when `git repack` was called with `-k`.

I think you might have missed the bigger problem I pointed at, as it was
buried deep within my later reply. Try applying this patch on top, which
tests the opposite case (reachable shallow commits are retained):

diff --git a/t/t5537-fetch-shallow.sh b/t/t5537-fetch-shallow.sh
index d32ba20f9d..911e457ae1 100755
--- a/t/t5537-fetch-shallow.sh
+++ b/t/t5537-fetch-shallow.sh
@@ -186,17 +186,20 @@ EOF
 	test_cmp expect actual
 '
 
-test_expect_success '.git/shallow is edited by repack' '
+test_expect_success 'set up shallow server' '
 	git init shallow-server &&
 	test_commit -C shallow-server A &&
 	test_commit -C shallow-server B &&
 	git -C shallow-server checkout -b branch &&
 	test_commit -C shallow-server C &&
 	test_commit -C shallow-server E &&
 	test_commit -C shallow-server D &&
 	d="$(git -C shallow-server rev-parse --verify D)" &&
-	git -C shallow-server checkout master &&
+	git -C shallow-server checkout master
+'
 
+test_expect_success 'repack drops unreachable objects from .git/shallow' '
+	test_when_finished "rm -rf shallow-client" &&
 	git clone --depth=1 --no-tags --no-single-branch \
 		"file://$PWD/shallow-server" shallow-client &&
 
@@ -213,4 +216,13 @@ test_expect_success '.git/shallow is edited by repack' '
 		origin "+refs/heads/*:refs/remotes/origin/*"
 '
 
+test_expect_success 'repack keeps reachable objects in .git/shallow' '
+	test_when_finished "rm -rf shallow-client" &&
+	git clone --depth=1 --no-tags --no-single-branch \
+		"file://$PWD/shallow-server" shallow-client &&
+
+	git -C shallow-client repack -adfl &&
+	grep $d shallow-client/.git/shallow
+'
+
 test_done