drush site-install fails for drupal6 on ubuntu 15-04

[Dan Kegel]

The procedure
    wget https://raw.githubusercontent.com/dankegel/busydrupal/master/migrate.sh
    sh migrate.sh deps
    sh migrate.sh install6
worked fine on Ubuntu 12.04 through 14.10, but as of Ubuntu 15.04, it fails quickly with

Starting Drupal installation. This takes a few seconds ... [ok]
Table "drupal6.variable" doesn"t exist [warning]
query: SELECT value FROM variable WHERE name =
"install_task" database.mysql.inc:135
Table "drupal6.variable" doesn"t exist [warning]
query: SELECT value FROM variable WHERE name =
"install_task" database.mysql.inc:135
The site install task '' failed. [error]

It's not doing much more than:
+ wget http://ftp.drupal.org/files/projects/drupal-6.35.tar.gz
+ tar -xf drupal-6.35.tar.gz
+ cd drupal-6.35
+ drush si default ...

and it's that last command that fails. Between Ubuntu 14.10 and 15.04, php was updated
from 5.5.12+dfsg-2ubuntu4.4 to 5.6.4+dfsg-4ubuntu6 and it's likely that drush and/or drupal6 itself
need updating to work with php 5.6.

The workaround from https://www.drupal.org/node/2465881, i.e. disable mbstring in php.ini, seems to let site-install succeed. (Probably need to disable it in both files /etc/php5/{apache2,cli}/php.ini.)

This is probably not really a bug in drush, but it appears to be one at first glance, so I'm filing this here in case anyone else runs into it.

ProblemType: Bug
DistroRelease: Ubuntu 15.04
Package: drush 5.10.0-2 [modified: usr/share/php/drush/commands/core/drupal/site_install_6.inc]
ProcVersionSignature: Ubuntu 3.19.0-16.16-generic 3.19.3
Uname: Linux 3.19.0-16-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 2.17.2-0ubuntu1
Architecture: amd64
CurrentDesktop: Unity
Date: Sun May 17 17:18:18 2015
InstallationDate: Installed on 2015-05-16 (1 days ago)
InstallationMedia: Ubuntu 15.04 "Vivid Vervet" - Release amd64 (20150422)
PackageArchitecture: all
SourcePackage: drush
UpgradeStatus: No upgrade log present (probably fresh install)

[Dan Kegel (dank)]

(btw the modifications to site_install_6.inc were just debug prints added after the problem occurred.)

[Dan Kegel (dank)]

Here's the workaround for drush (probably need to apply to /etc/php5/apache2/php.ini as well):

--- etc/php5/cli/php.ini.bak 2015-05-17 19:49:14.893316566 -0700
+++ etc/php5/cli/php.ini 2015-05-17 19:50:58.822103819 -0700
@@ -1698,7 +1698,7 @@
 ; If empty, default_charset or input_encoding or mbstring.input is used.
 ; The precedence is: default_charset < intput_encoding < mbsting.http_input
 ; http://php.net/mbstring.http-input
-;mbstring.http_input =
+mbstring.http_input = pass

 ; Use of this INI entry is deprecated, use global output_encoding instead.
 ; http output encoding.
@@ -1708,7 +1708,7 @@
 ; To use an output encoding conversion, mbstring's output handler must be set
 ; otherwise output encoding conversion cannot be performed.
 ; http://php.net/mbstring.http-output
-;mbstring.http_output =
+mbstring.http_output = pass

 ; enable automatic encoding translation according to
 ; mbstring.internal_encoding setting. Input chars are

[Dan Kegel (dank)]

drupal 6 is EOL in Feb 2016, https://www.drupal.org/drupal-6-eol

Can probably close then regardless.