Disable save of global git config

[MarkRx]

Description

JGit attempts to automatically save the user's .gitconfig file but this is not always desirable. In our CI/CD environment we set .gitconfig as immutable (+i in linux) to prevent builds from changing settings that may effect other builds. JGit will log the following error when it attempts to save.

I would like to be able to disable saving so that we only read from the user config and potentially make in-memory only config changes but never modify the underlying user config file.

Cannot save config file 'FileBasedConfig[/home/jenkins/.gitconfig]'
java.io.IOException: Cannot commit write to /home/jenkins/.gitconfig
 	at org.eclipse.jgit.storage.file.FileBasedConfig.save(FileBasedConfig.java:258)
 	at org.eclipse.jgit.util.FS$FileStoreAttributes.saveToConfig(FS.java:584)
 	at org.eclipse.jgit.util.FS$FileStoreAttributes.lambda$0(FS.java:364)
 	at java.base/java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1768)
 	at java.base/java.util.concurrent.CompletableFuture$AsyncSupply.exec(CompletableFuture.java:1760)
 	at java.base/java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:373)
 	at java.base/java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(ForkJoinPool.java:1182)
 	at java.base/java.util.concurrent.ForkJoinPool.scan(ForkJoinPool.java:1655)
 	at java.base/java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1622)
 	at java.base/java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:165)

Motivation

Preventing saving of the user .gitconfig when using jgit.

Alternatives considered

None. The stack is printed to the logs but ignored.

Additional context

No response