[PATCH v2 1/2] fast-import: add a test for tree delta base corruption

[Dmitry Ivankov <divanorama@gmail.com>]

fast-import is able to write imported tree objects in delta format.
It holds a tree structure in memory where each tree entry may have
a delta base sha1 assigned. When delta base data is needed it is
reconstructed from this in-memory structure. Though sometimes the
delta base data doesn't match the delta base sha1 so wrong or even
corrupt pack is produced.

Add a small test that produces a corrupt pack. It uses just tree
copy and file modification commands aside from the very basic commit
and blob commands.

Signed-off-by: Dmitry Ivankov <divanorama@gmail.com>
---
 t/t9300-fast-import.sh |   41 +++++++++++++++++++++++++++++++++++++++++
 1 files changed, 41 insertions(+), 0 deletions(-)

diff --git a/t/t9300-fast-import.sh b/t/t9300-fast-import.sh
index f256475..e2b94b5 100755
--- a/t/t9300-fast-import.sh
+++ b/t/t9300-fast-import.sh
@@ -734,6 +734,47 @@ test_expect_success \
 	 git diff-tree --abbrev --raw L^ L >output &&
 	 test_cmp expect output'
 
+cat >input <<INPUT_END
+blob
+mark :1
+data <<EOF
+the data
+EOF
+
+commit refs/heads/L2
+committer C O Mitter <committer@example.com> 1112912473 -0700
+data <<COMMIT
+init L2
+COMMIT
+M 644 :1 a/b/c
+M 644 :1 a/b/d
+M 644 :1 a/e/f
+
+commit refs/heads/L2
+committer C O Mitter <committer@example.com> 1112912473 -0700
+data <<COMMIT
+update L2
+COMMIT
+C a g
+C a/e g/b
+M 644 :1 g/b/h
+INPUT_END
+
+cat <<EOF >expect
+g/b/f
+g/b/h
+EOF
+
+test_expect_failure \
+    'L: nested tree copy does not corrupt deltas' \
+	'git fast-import <input &&
+	git ls-tree L2 g/b/ >tmp &&
+	cat tmp | cut -f 2 >actual &&
+	test_cmp expect actual &&
+	git fsck `git rev-parse L2`'
+
+git update-ref -d refs/heads/L2
+
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 ### series M
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1.7.3.4