For some reason this doesn't happen on my local machine but does happen on the prototype server.
When I run maintenance scripts, I get lots of warnings like these:
Warning: fopen(): cannot seek on a pipe in /srv/org/wikimedia/prototype/wikis/rl2/maintenance/Maintenance.php on line 313
Call Stack:
0.0004 154088 1. {main}() /srv/org/wikimedia/prototype/wikis/rl2/maintenance/update.php:0
0.0026 782096 2. require_once('/srv/org/wikimedia/prototype/wikis/rl2/maintenance/doMaintenance.php') /srv/org/wikimedia/prototype/wikis/rl2/maintenance/update.php:147
0.0995 12657528 3. UpdateMediaWiki->execute() /srv/org/wikimedia/prototype/wikis/rl2/maintenance/doMaintenance.php:105
10.8290 19037824 4. Maintenance->output() /srv/org/wikimedia/prototype/wikis/rl2/maintenance/update.php:128
10.8290 19037824 5. fopen() /srv/org/wikimedia/prototype/wikis/rl2/maintenance/Maintenance.php:313The offending line is $f = fopen( 'php://stdout', 'a' );
Version: unspecified
Severity: normal