I have been getting the following exception when trying to get an existing sha passed from an upstream job:

Started by upstream project "fptools_gcc-25x_test" build number 558 originally caused by:
Started by upstream project "fptools_gcc-25x" build number 630 originally caused by:
Started by an SCM change
[EnvInject] - Loading node environment variables.
Building on master in workspace <http://jenkins-cam-04.cam.broadcom.com/job/fptools_gcc-25x_test/archs=fp4014/ws/>
Fetching changes from the remote Git repository Fetching upstream changes from dsl-git@eng-cbga-2.cam.broadcom.com:tools/fp_gcc
Checking out Revision 79c8eb3d846d09ecedf3b331942d8904cdedf515 (origin/FP_GCC_2_5_X_BRANCH)
ERROR: Timeout after 10 minutes
FATAL: Could not checkout null with start point 79c8eb3d846d09ecedf3b331942d8904cdedf515
hudson.plugins.git.GitException: Could not checkout null with start point 79c8eb3d846d09ecedf3b331942d8904cdedf515
at org.jenkinsci.plugins.gitclient.CliGitAPIImpl.checkoutBranch(CliGitAPIImpl.java:1309)
at hudson.plugins.git.GitSCM.checkout(GitSCM.java:888)
at hudson.model.AbstractProject.checkout(AbstractProject.java:1411)
at hudson.model.AbstractBuild$AbstractBuildExecution.defaultCheckout(AbstractBuild.java:652)
at jenkins.scm.SCMCheckoutStrategy.checkout(SCMCheckoutStrategy.java:88)
at hudson.model.AbstractBuild$AbstractBuildExecution.run(AbstractBuild.java:561)
at hudson.model.Run.execute(Run.java:1665)
at hudson.matrix.MatrixRun.run(MatrixRun.java:146)
at hudson.model.ResourceController.execute(ResourceController.java:88)
at hudson.model.Executor.run(Executor.java:246)
Caused by: hudson.plugins.git.GitException: Command "git checkout -f 79c8eb3d846d09ecedf3b331942d8904cdedf515" returned status code 143:
stdout:
stderr:
at org.jenkinsci.plugins.gitclient.CliGitAPIImpl.launchCommandIn(CliGitAPIImpl.java:1183)
at org.jenkinsci.plugins.gitclient.CliGitAPIImpl.launchCommandIn(CliGitAPIImpl.java:1160)
at org.jenkinsci.plugins.gitclient.CliGitAPIImpl.launchCommandIn(CliGitAPIImpl.java:1156)
at org.jenkinsci.plugins.gitclient.CliGitAPIImpl.launchCommand(CliGitAPIImpl.java:972)
at org.jenkinsci.plugins.gitclient.CliGitAPIImpl.launchCommand(CliGitAPIImpl.java:982)
at org.jenkinsci.plugins.gitclient.CliGitAPIImpl.checkout(CliGitAPIImpl.java:1283)
at hudson.plugins.git.GitAPI.checkout(GitAPI.java:208)
at org.jenkinsci.plugins.gitclient.CliGitAPIImpl.checkoutBranch(CliGitAPIImpl.java:1293)
... 9 more