Merge branch 'mb/fast-import-delete-root' into maint

An attempt to remove the entire tree in the "git fast-import" input
stream caused it to misbehave.

* mb/fast-import-delete-root:
  fast-import: fix segfault in store_tree()
  t9300: test filedelete command

fast-import.c

@@ -1422,7 +1422,7 @@ static void mktree(struct tree_content *t, int v, struct strbuf *b)
 
 static void store_tree(struct tree_entry *root)
 {
-	struct tree_content *t = root->tree;
+	struct tree_content *t;
 	unsigned int i, j, del;
 	struct last_object lo = { STRBUF_INIT, 0, 0, /* no_swap */ 1 };
 	struct object_entry *le = NULL;
@@ -1430,6 +1430,10 @@ static void store_tree(struct tree_entry *root)
 	if (!is_null_sha1(root->versions[1].sha1))
 		return;
 
+	if (!root->tree)
+		load_tree(root);
+	t = root->tree;
+
 	for (i = 0; i < t->entry_count; i++) {
 		if (t->entries[i]->tree)
 			store_tree(t->entries[i]);

t/t9300-fast-import.sh

@@ -3017,4 +3017,108 @@ test_expect_success 'T: empty reset doesnt delete branch' '
 	git rev-parse --verify refs/heads/not-to-delete
 '
 
+###
+### series U (filedelete)
+###
+
+cat >input <<INPUT_END
+commit refs/heads/U
+committer $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL> $GIT_COMMITTER_DATE
+data <<COMMIT
+test setup
+COMMIT
+M 100644 inline hello.c
+data <<BLOB
+blob 1
+BLOB
+M 100644 inline good/night.txt
+data <<BLOB
+sleep well
+BLOB
+M 100644 inline good/bye.txt
+data <<BLOB
+au revoir
+BLOB
+
+INPUT_END
+
+test_expect_success 'U: initialize for U tests' '
+	git fast-import <input
+'
+
+cat >input <<INPUT_END
+commit refs/heads/U
+committer $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL> $GIT_COMMITTER_DATE
+data <<COMMIT
+delete good/night.txt
+COMMIT
+from refs/heads/U^0
+D good/night.txt
+
+INPUT_END
+
+test_expect_success 'U: filedelete file succeeds' '
+	git fast-import <input
+'
+
+cat >expect <<EOF
+:100644 000000 2907ebb4bf85d91bf0716bb3bd8a68ef48d6da76 0000000000000000000000000000000000000000 D	good/night.txt
+EOF
+
+git diff-tree -M -r U^1 U >actual
+
+test_expect_success 'U: validate file delete result' '
+	compare_diff_raw expect actual
+'
+
+cat >input <<INPUT_END
+commit refs/heads/U
+committer $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL> $GIT_COMMITTER_DATE
+data <<COMMIT
+delete good dir
+COMMIT
+from refs/heads/U^0
+D good
+
+INPUT_END
+
+test_expect_success 'U: filedelete directory succeeds' '
+	git fast-import <input
+'
+
+cat >expect <<EOF
+:100644 000000 69cb75792f55123d8389c156b0b41c2ff00ed507 0000000000000000000000000000000000000000 D	good/bye.txt
+EOF
+
+git diff-tree -M -r U^1 U >actual
+
+test_expect_success 'U: validate directory delete result' '
+	compare_diff_raw expect actual
+'
+
+cat >input <<INPUT_END
+commit refs/heads/U
+committer $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL> $GIT_COMMITTER_DATE
+data <<COMMIT
+must succeed
+COMMIT
+from refs/heads/U^0
+D ""
+
+INPUT_END
+
+test_expect_success 'U: filedelete root succeeds' '
+    git fast-import <input
+'
+
+cat >expect <<EOF
+:100644 000000 c18147dc648481eeb65dc5e66628429a64843327 0000000000000000000000000000000000000000 D	hello.c
+EOF
+
+git diff-tree -M -r U^1 U >actual
+
+test_expect_success 'U: validate root delete result' '
+	compare_diff_raw expect actual
+'
+
 test_done