After a recent update, SSH with SourceTree broke on me.
On my private repos I only allow modern, secure SSH ciphers. This used to work fine, but now I get a "No matching cipher found" error anytime I try to fetch or push. It looks like the official Windows Git comes bundled with an old or crippled OpenSSH client that doesn't support modern ciphers.
For command line usage, I was able to work around this by setting the GIT_SSH variable to point to my Cygwin SSH client. But, SourceTree doesn't seem to respect this setting and still tries to use the bundled SSH client.
Any ideas on how I can work around this?