Just picking out one case (algo 0: RSA-1024 with SHA-1), gen_test_cases.sh does this:

build/install_for_test/bin/signature_digest_utility 0 tests/testcases/test_file | openssl rsautl -sign -pkcs -inkey tests/testkeys/key_rsa1024.pem > tests/testcases/test_file.rsa1024_sha1.sig

And vb2_rsa_tests.sh does this to verify the signature:

build/install_for_test/bin/verify_data 0 tests/testkeys/key_rsa1024.keyb tests/testcases/test_file.rsa1024_sha1.sig tests/testcases/test_file

I did a bisect and this turns out to be the first bad commit:

commit 46a382d6136f2fd206fd8c95180dbb816c9ad5ce
Author: Randall Spangler <rspangler@chromium.org>
Date:   Tue Oct 18 12:00:07 2016 -0700

    vboot: Remove vboot1 cryptolib padding source
    
    The old vboot1 cryptolib hard-coded many of its padding arrays in a
    padding.c file.  Use the equivalent vboot2 apis instead.
    
    This change is almost exclusively on the host and test side; the only
    firmware impact is on a single line of debug output.
    
    BUG=chromium:611535
    BRANCH=none
    TEST=make runtests; emerge-kevin coreboot depthcharge
    
    Change-Id: If689ffd92f0255847bea2424950da4547b2c0df3
    Signed-off-by: Randall Spangler <rspangler@chromium.org>
    Reviewed-on: https://chromium-review.googlesource.com/400902
    Reviewed-by: Daisuke Nojiri <dnojiri@chromium.org>

Basically, signature_digest_utility now returns nothing:
build/install_for_test/bin/signature_digest_utility 0 tests/testcases/test_file | wc
      0       0       0
(returns error code 255, actually)

While, before that commit, it would output something sensible:
build/install_for_test/bin/signature_digest_utility 0 tests/testcases/test_file | hexdump -C
00000000  30 21 30 09 06 05 2b 0e  03 02 1a 05 00 04 14 bb  |0!0...+.........|
00000010  bc 03 28 c7 5c 1a 04 bb  f1 6d 80 25 7e 6c 38 4b  |..(.\....m.%~l8K|
00000020  21 4a 6f                                          |!Jo|

Anyway, fix is here: https://chromium-review.googlesource.com/439086 .

I'm not sure what's the impact of this bug, but it seems like it only affects signature_digest_utility, which may accidentally include the wrong digestinfo if VB2 algorithm happens to be a valid hash_halg, e.g. build/install_for_test/bin/signature_digest_utility 3 tests/testcases/test_file does output something.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/platform/vboot_reference/+/0bde10afbfa8753521b1d10d89b5409d4d1ad1f2

commit 0bde10afbfa8753521b1d10d89b5409d4d1ad1f2
Author: Nicolas Boichat <drinkcat@google.com>
Date: Sat Feb 11 10:42:01 2017

signature_digest/SignatureDigest: convert vb2_crypto to hash algorithm

We were passing the wrong value to PrependDigestInfo. Let's also refactor
the function a little bit.

BRANCH=none
BUG= chromium:689371 
TEST=make gentestcases; git status => no change

Change-Id: I0244c3f3de05b33b7ddd21e93a266faf34f2c239
Reviewed-on: https://chromium-review.googlesource.com/439086
Commit-Ready: Nicolas Boichat <drinkcat@chromium.org>
Tested-by: Nicolas Boichat <drinkcat@chromium.org>
Reviewed-by: Randall Spangler <rspangler@chromium.org>
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>

[modify] https://crrev.com/0bde10afbfa8753521b1d10d89b5409d4d1ad1f2/host/lib/signature_digest.c

Fixed. I can't find any uses of signature_digest_utility in our code, expect for that specific case generation shell script, so I believe this bug had no impact.