`org.eclipse.jgit.errors.ConfigInvalidException: Invalid line in config file` on test-ibm-aix73-ppc64_be-5

The failure is a malformed JGit user config at /home/iojs/.config/jgit/config on the Jenkins agent test-ibm-aix73-ppc64_be-5, hit while running git config --add remote.origin.fetch during checkout. Start with the top of the stack trace, which shows Config.fromText rejecting an invalid line in that file. Done means jobs on that node check out successfully again. Fixing it requires access to the CI host, so confirm with maintainers before starting.

Jobs on test-ibm-aix73-ppc64_be-5 are failing with,
e.g. https://ci.nodejs.org/job/node-test-commit-aix/nodes=aix73-power9/66061/console

18:03:25  > git config --add remote.origin.fetch +refs/pull/981/head:refs/remotes/origin/_jenkins_local_branch # timeout=30
18:03:29 org.eclipse.jgit.errors.ConfigInvalidException: Invalid line in config file
18:03:29 	at PluginClassLoader for git-client//org.eclipse.jgit.lib.Config.fromTextRecurse(Config.java:1445)
18:03:29 	at PluginClassLoader for git-client//org.eclipse.jgit.lib.Config.fromText(Config.java:1373)
18:03:29 	at PluginClassLoader for git-client//org.eclipse.jgit.storage.file.FileBasedConfig.load(FileBasedConfig.java:164)
18:03:29 	at PluginClassLoader for git-client//org.eclipse.jgit.util.FileUtils.readWithRetries(FileUtils.java:733)
18:03:29 	at PluginClassLoader for git-client//org.eclipse.jgit.storage.file.FileBasedConfig.load(FileBasedConfig.java:128)
18:03:29 Caused: org.eclipse.jgit.errors.ConfigInvalidException: Cannot read file /home/iojs/.config/jgit/config
18:03:29 	at PluginClassLoader for git-client//org.eclipse.jgit.storage.file.FileBasedConfig.load(FileBasedConfig.java:137)
18:03:29 	at PluginClassLoader for git-client//org.eclipse.jgit.util.SystemReader.updateAll(SystemReader.java:544)
18:03:29 	at PluginClassLoader for git-client//org.eclipse.jgit.util.SystemReader.getJGitConfig(SystemReader.java:435)
18:03:29 	at PluginClassLoader for git-client//org.eclipse.jgit.util.SystemReader.getSystemConfig(SystemReader.java:457)
18:03:29 	at PluginClassLoader for git-client//org.eclipse.jgit.util.SystemReader.getUserConfig(SystemReader.java:405)
18:03:29 	at PluginClassLoader for git-client//org.eclipse.jgit.internal.storage.file.FileRepository.<init>(FileRepository.java:161)
18:03:29 Caused: java.io.IOException: Cannot read file /home/iojs/.config/jgit/config
18:03:29 	at PluginClassLoader for git-client//org.eclipse.jgit.internal.storage.file.FileRepository.<init>(FileRepository.java:164)
18:03:29 	at PluginClassLoader for git-client//org.eclipse.jgit.lib.BaseRepositoryBuilder.build(BaseRepositoryBuilder.java:679)
18:03:29 	at PluginClassLoader for git-client//org.jenkinsci.plugins.gitclient.CliGitAPIImpl.getRepository(CliGitAPIImpl.java:3608)
18:03:29 Also:   hudson.remoting.Channel$CallSiteStackTrace: Remote call to JNLP4-connect connection from 3c.73.36a9.ip4.static.sl-reverse.com/169.54.115.60:32776
18:03:29 		at hudson.remoting.Channel.attachCallSiteStackTrace(Channel.java:1916)
18:03:29 		at hudson.remoting.UserRequest$ExceptionResponse.retrieve(UserRequest.java:384)
18:03:29 		at hudson.remoting.Channel.call(Channel.java:1108)
18:03:29 		at hudson.remoting.RemoteInvocationHandler.invoke(RemoteInvocationHandler.java:306)
18:03:29 		at PluginClassLoader for git-client/jdk.proxy72/jdk.proxy72.$Proxy147.withRepository(Unknown Source)
18:03:29 		at PluginClassLoader for git-client//org.jenkinsci.plugins.gitclient.RemoteGitImpl.withRepository(RemoteGitImpl.java:264)
18:03:29 		at PluginClassLoader for git//jenkins.plugins.git.GitHooksConfiguration.configure(GitHooksConfiguration.java:104)
18:03:29 		at PluginClassLoader for git//jenkins.plugins.git.GitHooksConfiguration.configure(GitHooksConfiguration.java:94)
18:03:29 		at PluginClassLoader for git//jenkins.plugins.git.GitHooksConfiguration.configure(GitHooksConfiguration.java:83)
18:03:29 		at PluginClassLoader for git//hudson.plugins.git.GitSCM.retrieveChanges(GitSCM.java:1231)
18:03:29 		at PluginClassLoader for git//hudson.plugins.git.GitSCM._checkout(GitSCM.java:1310)
18:03:29 		at PluginClassLoader for git//hudson.plugins.git.GitSCM.checkout(GitSCM.java:1277)
18:03:29 		at hudson.scm.SCM.checkout(SCM.java:540)
18:03:29 		at hudson.model.AbstractProject.checkout(AbstractProject.java:1254)
18:03:29 		at hudson.model.AbstractBuild$AbstractBuildExecution.defaultCheckout(AbstractBuild.java:648)
18:03:29 		at jenkins.scm.SCMCheckoutStrategy.checkout(SCMCheckoutStrategy.java:84)
18:03:29 		at hudson.model.AbstractBuild$AbstractBuildExecution.run(AbstractBuild.java:521)
18:03:29 		at hudson.model.Run.execute(Run.java:1849)
18:03:29 		at PluginClassLoader for matrix-project//hudson.matrix.MatrixRun.run(MatrixRun.java:153)
18:03:29 		at hudson.model.ResourceController.execute(ResourceController.java:97)
18:03:29 		at hudson.model.Executor.run(Executor.java:456)
18:03:29 Caused: hudson.plugins.git.GitException
18:03:29 	at PluginClassLoader for git-client//org.jenkinsci.plugins.gitclient.CliGitAPIImpl.getRepository(CliGitAPIImpl.java:3610)
18:03:29 	at PluginClassLoader for git-client//hudson.plugins.git.GitAPI.getRepository(GitAPI.java:349)
18:03:29 	at PluginClassLoader for git-client//org.jenkinsci.plugins.gitclient.AbstractGitAPIImpl.withRepository(AbstractGitAPIImpl.java:27)
18:03:29 	at PluginClassLoader for git-client//org.jenkinsci.plugins.gitclient.CliGitAPIImpl.withRepository(CliGitAPIImpl.java:83)
18:03:29 	at [email protected]/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(Unknown Source)
18:03:29 	at [email protected]/java.lang.reflect.Method.invoke(Unknown Source)
18:03:29 	at app//hudson.remoting.RemoteInvocationHandler$RPCRequest.perform(RemoteInvocationHandler.java:986)
18:03:29 	at app//hudson.remoting.RemoteInvocationHandler$RPCRequest.call(RemoteInvocationHandler.java:961)
18:03:29 	at app//hudson.remoting.RemoteInvocationHandler$RPCRequest.call(RemoteInvocationHandler.java:907)
18:03:29 	at app//hudson.remoting.UserRequest.perform(UserRequest.java:225)
18:03:29 	at app//hudson.remoting.UserRequest.perform(UserRequest.java:50)
18:03:29 	at app//hudson.remoting.Request$2.run(Request.java:391)
18:03:29 	at app//hudson.remoting.InterceptingExecutorService.lambda$wrap$0(InterceptingExecutorService.java:81)
18:03:29 	at [email protected]/java.util.concurrent.FutureTask.run(Unknown Source)
18:03:29 	at [email protected]/java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
18:03:29 	at [email protected]/java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
18:03:29 	at app//hudson.remoting.Engine$1.lambda$newThread$0(Engine.java:312)
18:03:29 	at [email protected]/java.lang.Thread.run(Unknown Source)
18:03:29 Caused: java.io.IOException
18:03:29 	at PluginClassLoader for git//hudson.plugins.git.GitSCM.checkout(GitSCM.java:1279)
18:03:29 	at hudson.scm.SCM.checkout(SCM.java:540)
18:03:29 	at hudson.model.AbstractProject.checkout(AbstractProject.java:1254)
18:03:29 	at hudson.model.AbstractBuild$AbstractBuildExecution.defaultCheckout(AbstractBuild.java:648)
18:03:29 	at jenkins.scm.SCMCheckoutStrategy.checkout(SCMCheckoutStrategy.java:84)
18:03:29 	at hudson.model.AbstractBuild$AbstractBuildExecution.run(AbstractBuild.java:521)
18:03:29 	at hudson.model.Run.execute(Run.java:1849)
18:03:29 	at PluginClassLoader for matrix-project//hudson.matrix.MatrixRun.run(MatrixRun.java:153)
18:03:29 	at hudson.model.ResourceController.execute(ResourceController.java:97)
18:03:29 	at hudson.model.Executor.run(Executor.java:456)
18:03:29 Performing Post build task...