When libsvn_ra_serf performs a 'HEAD' request as part of the commit handling,
and this request isn't pre-authenticated (E.g. one request per connection) the
request isn't retried with authentication.
This problem is caused by a bug in 'serf' which was fixed in serf trunk in
This problem can be seen as a
$ svn ci test2.txt --message "test 1.8.1 checkin"
svn: E155011: Commit failed (details follow):
svn: E155011: File 'C:\SVN_Test\test2.txt' is out of date
svn: E175005: File 'test2.txt' already exists
Because Subversion (pre r1526439) handled every HTTP status except 404 as a
trigger to report that the file already existed.
r1526439 updates the libsvn_ra_serf behavior to show different errors for
unexpected status codes.