On gnupg-2.1.12, gpg --update-trustdb result in a segfault. gnupg-2.1.11 work
fine on my keyring. Unfortunately I was not able to reproduce on a new keyring

Architecture used: Arch Linux
libgcrypt: 1.7.0 (same results with libgcrypt 1.6.5)

I've attached a gdb session containing the bug and basic debugging information

I've run a git bisect, using '''./autogen.sh && ./configure
--enable-maintainer-mode --enable-symcryptrun --prefix=/tmp/gnupg && make &&
make install && /tmp/gnupg/bin/gpg2 --update-trustdb''' to check the status.
Results are:
% git bisect log

git bisect start

bad: [00df5b1236cac5c7a48638a4613278c5aab486f8] Release 2.1.12

git bisect bad 00df5b1236cac5c7a48638a4613278c5aab486f8

good: [e9e5e83ec14459c2fc9060c54fc8e7381b541acd] Release 2.1.11

git bisect good e9e5e83ec14459c2fc9060c54fc8e7381b541acd

bad: [7a32f87cccddb40521bfdd4eb2d0dc9c88fb3fe5] scd: Bug fix for a device with

multiple interfaces.
git bisect bad 7a32f87cccddb40521bfdd4eb2d0dc9c88fb3fe5

bad: [b0125ae9850973b89010517b1dbce04125a51d51] common/exechelp: Fix pipe

creation.
git bisect bad b0125ae9850973b89010517b1dbce04125a51d51

good: [86f3bb144ad75461eb9b7ac1e59046ac75efccac] g13: Require a confirmation

before g13 is used for DM-Crypt.
git bisect good 86f3bb144ad75461eb9b7ac1e59046ac75efccac

good: [44b02e1beb4f38f26551d932827d5317fddd27c2] w32: Do not error out if

gpgconf is not installed.
git bisect good 44b02e1beb4f38f26551d932827d5317fddd27c2

good: [10671c3a4c18ea26035a5819a9f2b8fd6c7e41ea] gpg: Use format_keyid rather

than manually formatting the keyid.
git bisect good 10671c3a4c18ea26035a5819a9f2b8fd6c7e41ea

bad: [44cdb9d73f1a0b7d2c8483a119b9c4d6caabc1ec] gpg: Split check_key_signature2.

git bisect bad 44cdb9d73f1a0b7d2c8483a119b9c4d6caabc1ec

good: [5fbd80579aea0f75ca1d2700515c5b8747a75c7d] gpg: Split

print_and_check_one_sig.
git bisect good 5fbd80579aea0f75ca1d2700515c5b8747a75c7d

first bad commit: [44cdb9d73f1a0b7d2c8483a119b9c4d6caabc1ec] gpg: Split

check_key_signature2.