Incorrect errno used in OpenWalSummaryFile()

Hi all,

While looking at walsummary.c for a different thread, I have bumped
into this code:
OpenWalSummaryFile(WalSummaryFile *ws, bool missing_ok)
[...]
    file = PathNameOpenFile(path, O_RDONLY);
    if (file < 0 && (errno != EEXIST || !missing_ok))
        ereport(ERROR,
                (errcode_for_file_access(),
                 errmsg("could not open file \"%s\": %m", path)));

And it seems to me that this EEXIST should be an ENOENT?  The top of
the function also documents that we want to handle an error when a
summary file does not exist.  The comment makes sense to me, not the
code.

It's also worth noting that this function has two callers, both use
missing_ok = false, meaning that the errno check does not really
matter today.  If someone plays with this code on HEAD or the
back-branches and decides to introduce a missing_ok=true call, it
could matter, so I'd rather not change this function signature.

This issue has been mentioned here as well, I've just bumped into it
independently a few hours ago:
https://www.postgresql.org/message-id/tencent_1CA40FCC21C1C770712BC089@qq.com

Regards,
--
Michael