fix: Mail Notification Failed: SecurityManager Not Available in Async Context (OD-2699)

Author: robinshine

server-core/src/main/java/io/onedev/server/mail/DefaultMailService.java

@@ -197,6 +197,7 @@ public void sendMailAsync(Collection<String> toList, Collection<String> ccList,
 							  @Nullable String senderName, @Nullable String references) {
 		transactionService.runAfterCommit(() -> executorService.execute(() -> {
 			try {
+				SecurityUtils.bindAsSystem();
 				sendMail(toList, ccList, bccList, subject, htmlBody, textBody, replyAddress, 
 						senderName, references);
 			} catch (Exception e) {

server-core/src/main/java/io/onedev/server/security/SecurityUtils.java

@@ -620,9 +620,12 @@ public static void bindAsSystem() {
 	}
 
 	public static Runnable inheritSubject(Runnable task) {
-		Subject subject = SecurityUtils.getSubject();
+        Subject subject = ThreadContext.getSubject();
 		return () -> {
-			ThreadContext.bind(subject);
+			if (subject != null)
+				ThreadContext.bind(subject);
+			else
+				ThreadContext.unbindSubject();
 			task.run();
 		};
 	}