WebInstaller_Install does not check for warnings from the installation steps, so failure of the mediawiki-announce subscription and the mt_rand() security warning are not reported to the user.
Also, the use of Http::post() instead of MWHttpRequest::factory()->execute() means that the status object generated by the Http module is thrown away. So very little information could be reported to the user even if warnings were checked for.
The subscription step failed for me once and then worked the next three times. I don't know why.
Version: 1.22.0
Severity: normal