Svn crash, related to --username?

Newest svn crashes, apparently from using the --username command line option.
We use MSBuild community tasks in our automated build. It attempts to issue subversion commands, and these commands work with older svn version 1.6.17, but fail with current versions. The commands are of the form:
svn.exe update "<server location>" "<local directory>" --username <name> --password <pass> --non-interactive --no-auth-cache
My attempts to investigate seem to show that the only part of that that is causing a crash individually is --username (possibly --password , too, I did not try with only the password option)
This happens with Sliksvn and collabnet svn.