GPG can use customized directories instead of the standard ~/.gnupg or
%APPDATA%\gnupg directories:
* Environment variable GNUPGHOME can define the location.
* On Windows, a registry key may define the location (but this is
deprecated).
* Portable installations may use a directory defined via a file
"gpgconf.ctl".
* GPG programs may take a --homedir command-line argument, which
overrides anything.
Implement handling of environment variable GNUPGHOME. The other ways of
GPG to get its home directory are outside the reach of JGit. Provide a
system property "jgit.gpg.home" that the user can set in such cases.
Do tilde replacement for the system property and for GNUPGHOME.
Note that on VMS, the default directory would be ~/gnupg (without dot).
This is not accounted for, but a user on VMS could now use either the
system property or GNUPGHOME to direct JGit to the right directory.
Bug: 575327
Change-Id: Id5ea04a85d58dba0c0df7a705777630d36042467
Signed-off-by: Thomas Wolf <thomas.wolf@paranor.ch>
ca7a30f231