I just did an svn switch from REL_1_16 to trunk, ran update.php and went to the main page, only to get a whole bunch of garbled output.
To cut a long story short, I tracked this down to the fact that the output was being compressed twice.
I have the following line in my LocalSettings.php:
if ( $wgCommandLineMode ) {
if ( isset( $_SERVER ) && array_key_exists( 'REQUEST_METHOD', $_SERVER ) ) {
die( "This script must be run from the command line\n" );
}
} elseif ( empty( $wgNoOutputBuffer ) ) {
- Compress output if the browser supports it
if( !ini_get( 'zlib.output_compression' ) ) @ob_start( 'ob_gzhandler' );
}
This line enables output buffering if it is not already enabled. The important thing to note here, is that this was automatically created by the installer script at the point I first installed MW, whenever that was. It is therefore very likely that a lot of users have this line in their LocalSettings.php, and will therefore suffer this same breakage when they upgrade to 1.17 unless this issue is fixed!
I tracked the problem down to r72349, where the logic for starting output buffering was changed in WebStart.php.
The old logic realised that buffering was started, and did nothing.
The new logic does not correctly detect this situation, so output buffering/compression is started, resulting in double-compression.
Version: 1.17.x
Severity: critical