Notice: Constant already defined in wp-config.php on (non-existent) line?

Question

I've been tasked to move a website into a new domain, and I've encontered this weird issue.
On the homepage, I always see these:

Notice: Constant AUTOSAVE_INTERVAL already defined in /home/gturnat/public_html/wp-config.php on line 99

Notice: Constant WP_POST_REVISIONS already defined in /home/gturnat/public_html/wp-config.php on line 100

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What I have tried:

• Notice: Constant WP_POST_REVISIONS already defined suggests commenting the constants on default-constants.php, but it doesn't work.
• Settings display_errors to 0, '0' or 'Off' does nothing.
• Running error_reporting(0) will still display the errors.
• Creating a mu-plugin (As suggested on How can I stop PHP notices from appearing in wordpress?).
  Nothing happens and the plugin isn't even loaded.
  The errors still keep showing up.
• Tried to comment out the lines in wp-config.php, but didn't work. The notices are still there.
• Removed the lines entirelly and moved them around wp-config.php, but the warnings insist it is on line 99 and 100.
  Causing a syntax error inside wp-config.php does lead to an error being logged, which means that the file isn't cached.
• Tried to enable and disable the debug mode, set display_errors to false, 0, '0' and 'Off', but doesn't work.
• Ran grep -1R WP_POST_REVISIONS * and grep -1R AUTOSAVE_INTERVAL * with the following result:

  root@webtest:# grep -lR WP_POST_REVISIONS *
  wp-config.php
  wp-includes/default-constants.php
  wp-includes/revision.php
  root@webtest:# grep -lR AUTOSAVE_INTERVAL *
  wp-config.php
  wp-includes/script-loader.php
  wp-includes/default-constants.php
  wp-includes/class-wp-customize-manager.php

I really am out of any other idea to try.

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I'm using Wordpress 4.7.2, running on PHP 5.4 with the following modules loaded:

There is no op-cache working in the server. Just those options.

PHP was configured with the following options:

'./configure' '--prefix=/usr' '--exec-prefix=/usr' '--bindir=/usr/bin' '--sbindir=/usr/sbin' '--sysconfdir=/etc' '--datadir=/usr/share' '--includedir=/usr/include' '--libdir=/usr/lib64' '--libexecdir=/usr/libexec' '--sharedstatedir=/var/lib' '--mandir=/usr/share/man' '--infodir=/usr/share/info' '--build=x86_64-redhat-linux-gnu' '--host=x86_64-redhat-linux-gnu' '--target=x86_64-redhat-linux-gnu' '--program-prefix=' '--prefix=/opt/alt/php54' '--exec-prefix=/opt/alt/php54' '--bindir=/opt/alt/php54/usr/bin' '--sbindir=/opt/alt/php54/usr/sbin' '--sysconfdir=/opt/alt/php54/etc' '--datadir=/opt/alt/php54/usr/share' '--includedir=/opt/alt/php54/usr/include' '--libdir=/opt/alt/php54/usr/lib64' '--libexecdir=/opt/alt/php54/usr/libexec' '--localstatedir=/var' '--sharedstatedir=/usr/com' '--mandir=/opt/alt/php54/usr/share/man' '--infodir=/opt/alt/php54/usr/share/info' '--cache-file=../config.cache' '--with-libdir=lib64' '--with-config-file-path=/opt/alt/php54/etc' '--with-config-file-scan-dir=/opt/alt/php54/link/conf' '--with-exec-dir=/usr/bin' '--with-layout=GNU' '--disable-debug' '--disable-rpath' '--without-pear' '--without-gdbm' '--with-pic' '--with-zlib' '--with-bz2' '--with-gettext' '--with-gmp' '--with-iconv' '--with-openssl' '--with-kerberos' '--with-mhash' '--with-readline' '--with-pcre-regex=/opt/alt/pcre/usr' '--with-libxml-dir=/opt/alt/libxml2/usr' '--with-curl=/opt/alt/curlssl/usr' '--enable-exif' '--enable-ftp' '--enable-magic-quotes' '--enable-shmop' '--enable-calendar' '--enable-xml' '--enable-force-cgi-redirect' '--enable-fastcgi' '--enable-pcntl' '--enable-bcmath=shared' '--enable-dba=shared' '--with-db4=/usr' '--enable-dbx=shared,/usr' '--enable-dom=shared' '--enable-fileinfo=shared' '--enable-intl=shared' '--enable-json=shared' '--enable-mbstring=shared' '--enable-mbregex' '--enable-pdo=shared' '--enable-phar=shared' '--enable-posix=shared' '--enable-soap=shared' '--enable-sockets=shared' '--enable-sqlite3=shared,/opt/alt/sqlite/usr' '--enable-sysvsem=shared' '--enable-sysvshm=shared' '--enable-sysvmsg=shared' '--enable-wddx=shared' '--enable-xmlreader=shared' '--enable-xmlwriter=shared' '--enable-zip=shared' '--with-gd=shared' '--enable-gd-native-ttf' '--with-jpeg-dir=/usr' '--with-freetype-dir=/usr' '--with-png-dir=/usr' '--with-xpm-dir=/usr' '--with-t1lib=/opt/alt/t1lib/usr' '--with-imap=shared' '--with-imap-ssl' '--with-xmlrpc=shared' '--with-ldap=shared' '--with-ldap-sasl' '--with-pgsql=shared' '--with-snmp=shared,/usr' '--enable-ucd-snmp-hack' '--with-xsl=shared,/usr' '--with-pdo-odbc=shared,unixODBC,/usr' '--with-pdo-pgsql=shared,/usr' '--with-pdo-sqlite=shared,/opt/alt/sqlite/usr' '--with-mssql=shared,/opt/alt/freetds/usr' '--with-interbase=shared,/usr' '--with-pdo-firebird=shared,/usr' '--with-pdo-dblib=shared,/opt/alt/freetds/usr' '--with-mcrypt=shared,/usr' '--with-tidy=shared,/usr' '--with-recode=shared,/usr' '--with-enchant=shared,/usr' '--with-pspell=shared' '--with-unixODBC=shared,/usr' '--with-icu-dir=/opt/alt/libicu/usr' '--with-sybase-ct=shared,/opt/alt/freetds/usr'

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As a testing point, I tried to run it on PHP 5.6, with the same results, with the following modules:

Answer 1

tl;dr: Clear your (Comet) Cache!

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Long answer:

I only have 2 words: Comet Cache!

Comet Cache was enabled.
Checking the source code showed me a note like this, after the closing </html>:

<!-- *´¨)
     ¸.•´¸.•*´¨) ¸.•*¨)
     (¸.•´ (¸.•` ¤ Comet Cache Notes ¤ ´¨) -->

<!-- Cache File Version Salt:       n/a -->

<!-- Cache File URL:                http://<my-domain> -->
<!-- Cache File Path:               /cache/comet-cache/cache/http/<my-domain>/index.html -->

<!-- Cache File Generated Via:      HTTP request -->
<!-- Cache File Generated On:       Feb 22nd, 2017 @ 5:37 pm UTC -->
<!-- Cache File Generated In:       4.59149 seconds -->

<!-- Cache File Expires On:         Mar 1st, 2017 @ 5:37 pm UTC -->
<!-- Cache File Auto-Rebuild On:    Mar 1st, 2017 @ 5:37 pm UTC -->

<!-- *´¨)
     ¸.•´¸.•*´¨) ¸.•*¨)
     (¸.•´ (¸.•` ¤ Comet Cache is Fully Functional ¤ ´¨) -->

<!-- Loaded via Cache On:    Feb 22nd, 2017 @ 5:37 pm UTC -->
<!-- Loaded via Cache In:    0.03472 seconds -->

Manually deleting /cache/comet-cache/cache/http/<my-domain>/index.html (path relative to your /wp-content/ directory) solved the issue.

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I feel so stupid for assuming that there was no caching going on. Always blame the cache!

Answer 2

If you do not have any plugin that manipulates those definitions, this is most likely cause by having the two constants defined below the line in the config.php that says

/* That's all, stop editing! Happy blogging. */

The relatively high line numbers support this idea.