KubeConfig.loadFromDefault currentContext is inconsistent with kubectl with multiple kubeconfigs

[adrianord]

When using multiple kubeconfigs through the KUBECONFIG environment variable, kubectl always uses the first file in the KUBECONFIG environment variable to grab the current context.

One example found here
https://github.com/kubernetes/kubectl/blob/952f50e545b14e0a2a0781ef47c342cdba5a8c54/pkg/cmd/config/current_context.go#L62-L76

However, because loadFromDefault uses mergeConfig, it always overwrites the currentContext with next kubeconfig it merges, causing it to use the last kubeconfig's context.

javascript/src/config.ts

Lines 234 to 245 in a8d4f1c

	public mergeConfig(config: KubeConfig): void {
	this.currentContext = config.currentContext;
	config.clusters.forEach((cluster: Cluster) => {
	this.addCluster(cluster);
	});
	config.users.forEach((user: User) => {
	this.addUser(user);
	});
	config.contexts.forEach((ctx: Context) => {
	this.addContext(ctx);
	});
	}

This causes using kubectl to change the context to not affect loadFromDefault when making CLI tools where the users sets the KUBECONFIG environment variable with multiple kubeconfigs since kubectl use-context sets the context in the first kubeconfig in the environment variable.
https://github.com/kubernetes/kubectl/blob/952f50e545b14e0a2a0781ef47c342cdba5a8c54/pkg/cmd/config/use_context.go#L65-L79