svn: E000032: Can't write to connection: Broken pipe

Dear Colleagues,

I have a very strange random problem with svnserve (subversion-1.7.10) on
FreeBSD. When trying to import sources into svn, I get the following
message at random moments:

$ svn import -m 'Imported from http://people.freebsd.org/~ae/' . svn://relay.sibptus.ru:3691/src/netmond-2.3.7
Adding trap.c
Adding mib.c
Adding variables.c
svn: E000032: Can't write to connection: Broken pipe
$

WireShark shows that the connection to svnserve is indeed abruptly terminated.

On the host running svnserve there is the following in syslog:

Aug 30 09:04:50 <auth.err> relay svnserve: encoded packet size too big (4156 > 4096)
Aug 30 09:05:03 <auth.err> relay svnserve: encoded packet size too big (4156 > 4096)

What could be the cause of the problem?

-- 
Victor Sudakov,  VAS4-RIPE, VAS47-RIPN
sip:sudakov_at_sibptus.tomsk.ru