Migration assistant

[Robert J. Hansen]

I'm dusting off an old set of scripts that I used to use for migrating
GnuPG instances from one machine to another.  I have to revisit some of
the logic to update it for GnuPG 2.1.  I know roughly what should be
here, but before I update the code and share it with the world I'd like
to have it *precisely* correct.

In GNUPG_HOME ($HOME/.gnupg, or %APPDIR%/GnuPG):

gpg-agent.conf
gpg.conf
pubring.gpg
secring.gpg
trustdb.gpg
pubring.kbx
sshcontrol
crls.d/*
openpgp-revocs.d/CUSTOM_LOGIC_1
private-keys-v1.d/CUSTOM_LOGIC_2

CUSTOM_LOGIC_1:
Iterate over all files in this directory
  If the filename could be a SHA-1 hexadecimal hash:
    If the filename ends in ".rev":
      If the file contents contains a line with ":-----BEGIN
      PGP PUBLIC KEY BLOCK-----":
        Flag this file for inclusion in the archive

CUSTOM_LOGIC_2:
Iterate over all files in this directory
  If the filename could be a SHA-1 hexadecimal hash:
    If the filename ends in ".key":
      Flag this file for inclusion in the archive

Do I have this correct?  Are there any files that I'm missing?  Is there
any better logic I can use for the contents of the crls.d/ subdirectory
except "better grab everything, I guess"?