TortoiseSVN using SSH
This problem is caused by the Subversion client libraries for Windows. It was introduced with version 1.9.0, and the fix will be released with 1.9.1 [1] [2] . So any windows client that is using it will not work with svn+ssh. TortoiseSVN is just one example, the same was observed with JavaHL/Subclipse, SmartSVN and the Subversion command line client itself.
Update: A downgrade to version 1.8.12 (which was released along with 1.9.0) helped in my case.[3]
[1] Subversion Dev: JavaHL, 1.9: "Bad file descriptor", "Stream doesn't support this capability" errors
[2] fixed with r1696225 (there is obviously no bug filed yet)