% create subversion repo
Checked out revision 0.
A         alpha
Adding         alpha
Transmitting file data .
Committed revision 1.
% create hg repo
% first revision, no sub
adding a
% add first svn sub
committing subrepository s
% debugsub
path s
 source   file:///root/svn-repo
 revision 1

% change file in svn and hg, commit
committing subrepository s
Sending        s/alpha
Transmitting file data .
Committed revision 2.
At revision 2.
path s
 source   file:///root/svn-repo
 revision 2

% should be empty despite change to s/a

% add a commit from svn
U    alpha
Updated to revision 2.
Sending        alpha
Transmitting file data .
Committed revision 3.
% this commit from hg will fail
committing subrepository s
abort: svn: Commit failed (details follow):
svn: File '/alpha' is out of date

% clone
updating to branch default
A    s/alpha
Checked out revision 2.
3 files updated, 0 files merged, 0 files removed, 0 files unresolved
% debugsub in clone
path s
 source   file:///root/svn-repo
 revision 2