Re: Infinite loop in XLogPageRead() on standby

I identified the cause of the second issue. When I tried to replay the
issue, the second standby accidentally received the old timeline's
last page-spanning record till the end while the first standby was
promoting (but it had not been read by recovery). In addition to that,
on the second standby, there's a time window where the timeline
increased but the first segment of the new timeline is not available
yet. In this case, the second standby successfully reads the
page-spanning record in the old timeline even after the second standby
noticed that the timeline ID has been increased, thanks to the
robustness of XLogFileReadAnyTLI().

Of course, regardless of the changes above, if recovery on the second
standby had reached the end of the page-spanning record before
redirection to the first standby, it would need pg_rewind to connect
to the first standby.