Re: [PATCH] Fix error message in RemoveWalSummaryIfOlderThan to indicate file removal failure

[zengman]

> Likely so.  This one should be backpatched, as the error generated
> could be confusing if faced.  That's very unlikely so, still..  I'll
> look at other places in the tree for similar inconsistencies, while on
> it.

Hi Michael,

Thank you for helping to address this! I??ve gone back and reviewed the code, 
and noticed `OpenWalSummaryFile`:
```
File
OpenWalSummaryFile(WalSummaryFile *ws, bool missing_ok)
{
        char            path[MAXPGPATH];
        File            file;

        snprintf(path, MAXPGPATH,
                         XLOGDIR "/summaries/%08X%08X%08X%08X%08X.summary",
                         ws->tli,
                         LSN_FORMAT_ARGS(ws->start_lsn),
                         LSN_FORMAT_ARGS(ws->end_lsn));

        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)));

        return file;
}
```
I??m thinking of changing `errno != EEXIST` to `errno != ENOENT` here ?? would 
you think this adjustment is appropriate?

--
Regards,
Man Zeng