Error: 

svn: E215000: GNOME Keyring is locked and we are non-interactive

Solution:

Edit the ~/.subversion/config with gedit or nano , and add the following

[auth]
password-stores=

Reason:

SVN can store it’s access credentials (i.e. user/password for the repo) in the GNOME key ring (A secure password store). Normally, if you’re in a shell opened by GNOME the key ring is unlocked and SVN gets the information it needs with no problems.

When you get a shell by some other means (e.g. ssh to a remote machine) the key ring stays locked and you need to enter a password to unlock it. SVN will prompt for the key ring password when you try to access the repository. hgsubversion doesn’t.