I use ssh keys with Jenkins to communicate with Github and Bitbucket. I've previously injected SSH_AUTH_SOCK env vars into jobs, until I installed the ssh-agent plugin yesterday, with the goal of using SSH keys to poll for changes, where environment variables aren't available.

After jumping through setup hoops and stripping out my SSH_AUTH_SOCK variables, when I manually start a build, Jenkins correctly uses its stored SSH key credential to access Bitbucket. However, job polling continues to fail with what appears to be an SSH authorization problem:

Started on Jan 4, 2014 5:16:17 PM
Using strategy: Default
[poll] Last Built Revision: Revision 0919a53989bdab78bcfb6b8626b8517d33006cdd (origin/develop)
FATAL: hudson.plugins.git.GitException: Command "git ls-remote -h git@bitbucket.org:companyname/companyname-ios-us.git develop" returned status code 128:
stdout: 
stderr: Permission denied (publickey).
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository exists.

hudson.util.IOException2: hudson.plugins.git.GitException: Command "git ls-remote -h git@bitbucket.org:companyname/companyname-ios-us.git develop" returned status code 128:
stdout: 
stderr: Permission denied (publickey).
fatal: Could not read from remote repository.

I've verified that the same SSH key that fails when polling is accepted for manually-invoked builds (there's only one Bitbucket SSH key stored in Jenkins). I removed the username from the example, but copied and pasted, `git ls-remote -h git@bitbucket.org:companyname/companyname-ios-us.git develop` does return valid data when run interactively under this same SSH key.

Further, I see the same authorization error at Github when I perform similar key setup and attempt to poll a Github project. The Github key likewise succeeds interactively, and in manual Jenkins builds.

I'm about out of ideas as to why ssh-agent is ineffective when Jenkins is polling, even while it says it's trying to use the correct key. Any suggestions or further inquiries would be welcome.