Set parentServerId for IMAP folders to prevent fixup code from resetting parentKey

b/11355523

Change-Id: Idbef28cdbbc0eac50552fabeb24e2ec49a6cd042
diff --git a/src/com/android/email/mail/store/ImapStore.java b/src/com/android/email/mail/store/ImapStore.java
index e68533a..b0c66c5 100644
--- a/src/com/android/email/mail/store/ImapStore.java
+++ b/src/com/android/email/mail/store/ImapStore.java
@@ -306,8 +306,9 @@
             final Mailbox mailbox = folder.mMailbox;
             int delimiterIdx = mailbox.mServerId.lastIndexOf(mailbox.mDelimiter);
             long parentKey = Mailbox.NO_MAILBOX;
+            String parentPath = null;
             if (delimiterIdx != -1) {
-                String parentPath = path.substring(0, delimiterIdx);
+                parentPath = path.substring(0, delimiterIdx);
                 final ImapFolder parentFolder = mailboxes.get(parentPath);
                 final Mailbox parentMailbox = (parentFolder == null) ? null : parentFolder.mMailbox;
                 if (parentMailbox != null) {
@@ -317,6 +318,7 @@
                 }
             }
             mailbox.mParentKey = parentKey;
+            mailbox.mParentServerId = parentPath;
         }
     }