Then, switch the default value to "0600", due to general security
concerns about terminals being written to by other users.
Closing #35599.
Backport note: the default is changed back to 0620 to keep backward
compatbility intact for the purpose of backporting. This lets
security-conscious users fix the issue if they want to, without
affecting users that do not want changes in the stable branches.
(cherry picked from commit a4d1891475)
Yu Watanabe
7adac4caec