git-svn fetch failure: index.lock file exists

Hi,

I've been using git-svn for a while now to work on gcc.  Last night, I did a

  git svn fetch

and got the following failure:

  Found possible branch point: svn+ssh://aaw@gcc.gnu.org/svn/gcc/trunk =>
      svn+ssh://aaw@gcc.gnu.org/svn/gcc/tags/libbid-last-merge, 128810
  Found branch parent: (tags/libbid-last-merge)
      789aa951bbc6a49f791bf5109136335fc33222c5
  fatal: unable to create
'.git/svn/tags/libbid-last-merge/index.lock': File exists
  read-tree 789aa951bbc6a49f791bf5109136335fc33222c5:
      command returned error: 128

Naively, it looks to me like I've just got a stale lock file from a
previous run.  However, I have no idea what the correct recovery
strategy is.  Can I just delete the lock file?  Do I need to do some
sort of data validation?

I'm using git version 1.5.2.5 with subversion version 1.4.5 (r25188).

Thanks,
Ollie