build failing with "FATAL: Command "reset --hard" returned status code 128:"

http://jenkins.ovirt.org/job/ovirt_engine_master_find_bugs_gerrit/3842/co... "If no other git process is currently running, this probably means a git process crashed in this repository earlier. Make sure no other git process is running and remove the file manually to continue. hudson.plugins.git.GitException: Command "reset --hard" returned status code 128: stdout: stderr: fatal: Unable to create '/home/jenkins/workspace/ovirt_engine_master_find_bugs_gerrit(a)2/ovirt-engine/.git/index.lock': File exists. If no other git process is currently running, this probably means a git process crashed in this repository earlier. Make sure no other git process is running and remove the file manually to continue. at org.jenkinsci.plugins.gitclient.CliGitAPIImpl.launchCommandIn(CliGitAPIImpl.java:940) at org.jenkinsci.plugins.gitclient.CliGitAPIImpl.launchCommandIn(CliGitAPIImpl.java:921) at org.jenkinsci.plugins.gitclient.CliGitAPIImpl.launchCommand(CliGitAPIImpl.java:865) at org.jenkinsci.plugins.gitclient.CliGitAPIImpl.reset(CliGitAPIImpl.java:221) at org.jenkinsci.plugins.gitclient.CliGitAPIImpl.clean(CliGitAPIImpl.java:334) at hudson.plugins.git.GitAPI.clean(GitAPI.java:251) at hudson.plugins.git.GitSCM$4.invoke(GitSCM.java:1228) at hudson.plugins.git.GitSCM$4.invoke(GitSCM.java:1211) at hudson.FilePath$FileCallableWrapper.call(FilePath.java:2394) at hudson.remoting.UserRequest.perform(UserRequest.java:118) at hudson.remoting.UserRequest.perform(UserRequest.java:48) at hudson.remoting.Request$2.run(Request.java:326) at hudson.remoting.InterceptingExecutorService$1.call(InterceptingExecutorService.java:72) at java.util.concurrent.FutureTask.run(FutureTask.java:262) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) at hudson.remoting.Engine$1$1.run(Engine.java:63) at java.lang.Thread.run(Thread.java:744)"