git svn: lookup new parents correctly from svn:mergeinfo
git svn: lookup new parents correctly from svn:mergeinfo

This appears to be a trivial case where array indices were being
passed to git rev-list, instead of the contents stored in the
array itself.

Signed-off-by: Eric Wong <8c2951295f8292b0c03727bc4652981172298eae@yhbt.net>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git