Fix task instance limit (#97011)

Fixes #96999

src/vs/workbench/contrib/tasks/browser/terminalTaskSystem.ts

@@ -229,6 +229,7 @@ export class TerminalTaskSystem implements ITaskSystem {
 	}
 
 	public run(task: Task, resolver: ITaskResolver, trigger: string = Triggers.command): ITaskExecuteResult {
+		task = task.clone(); // A small amount of task state is stored in the task (instance) and tasks passed in to run may have that set already.
 		const recentTaskKey = task.getRecentlyUsedKey() ?? '';
 		let validInstance = task.runOptions && task.runOptions.instanceLimit && this.instances[recentTaskKey] && this.instances[recentTaskKey].instances < task.runOptions.instanceLimit;
 		let instance = this.instances[recentTaskKey] ? this.instances[recentTaskKey].instances : 0;

src/vs/workbench/contrib/tasks/common/tasks.ts

@@ -688,6 +688,10 @@ export class CustomTask extends CommonTask {
 		}
 	}
 
+	public clone(): CustomTask {
+		return new CustomTask(this._id, this._source, this._label, this.type, this.command, this.hasDefinedMatchers, this.runOptions, this.configurationProperties);
+	}
+
 	public customizes(): KeyedTaskIdentifier | undefined {
 		if (this._source && this._source.customizes) {
 			return this._source.customizes;
@@ -874,6 +878,10 @@ export class ContributedTask extends CommonTask {
 		this.command = command;
 	}
 
+	public clone(): ContributedTask {
+		return new ContributedTask(this._id, this._source, this._label, this.type, this.defines, this.command, this.hasDefinedMatchers, this.runOptions, this.configurationProperties);
+	}
+
 	public getDefinition(): KeyedTaskIdentifier {
 		return this.defines;
 	}
@@ -938,6 +946,10 @@ export class InMemoryTask extends CommonTask {
 		this._source = source;
 	}
 
+	public clone(): InMemoryTask {
+		return new InMemoryTask(this._id, this._source, this._label, this.type, this.runOptions, this.configurationProperties);
+	}
+
 	public static is(value: any): value is InMemoryTask {
 		return value instanceof InMemoryTask;
 	}