+
+ # for compatibility with existing ssoma installations
+ # we can probably remove this entirely by 2020
+ my $git_dir = $self->{git}->{git_dir};
+ my $index = "$git_dir/ssoma.index";
+ # XXX: change the following scope to: if (-e $index) # in 2018 or so..
+ unless ($ENV{FAST}) {
+ local $ENV{GIT_INDEX_FILE} = $index;
+ system('git', "--git-dir=$git_dir", qw(read-tree -m -v -i),
+ $self->{ref}) == 0 or
+ die "failed to update $git_dir/ssoma.index: $?\n";
+ }
+
+