gpg --verify has race conditions when used concurrently

There is a race condition with gnupg --verify when multiple processes
act at the same time.
strace helps cause the race condition (probably by slowing thing down)
gpgv does not seem to have the issue.

The result is you will see transient verify failures with output like below.
using '--lock-once' seems to improve the problem, but not to entirely fix it.

gpg: Signature made Fri 10 Jan 2014 05:41:43 PM UTC using DSA key ID 437D05B5
gpg: 12: read expected rec type 10, got 0
gpg: lookup_hashtable failed: trust database error
gpg: trustdb: searching trust record failed: trust database error
gpg: Error: The trustdb is corrupted.
gpg: You may try to re-create the trustdb using the commands:
gpg: cd ~/.gnupg
gpg: gpg2 --export-ownertrust > otrust.tmp
gpg: rm trustdb.gpg
gpg: gpg2 --import-ownertrust < otrust.tmp
gpg: If that does not work, please consult the manual

See the attached 'verify-race' to show the issue.

ProblemType: Bug
DistroRelease: Ubuntu 14.10
Package: gnupg 1.4.16-1.2ubuntu1
ProcVersionSignature: User Name 3.16.0-3.8-generic 3.16.0-rc4
Uname: Linux 3.16.0-3-generic x86_64
ApportVersion: 2.14.4-0ubuntu2
Architecture: amd64
Date: Wed Jul 16 16:09:42 2014
Ec2AMI: ami-0000002c
Ec2AMIManifest: FIXME
Ec2AvailabilityZone: nova
Ec2InstanceType: m1.small
Ec2Kernel: aki-00000002
Ec2Ramdisk: ari-00000002
ProcEnviron:
 TERM=xterm
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: gnupg
UpgradeStatus: No upgrade log present (probably fresh install)