Change 434710 had a related patch set uploaded (by Reedy; owner: Reedy):
[operations/puppet@production] Remove pear packages from MW Application Servers

https://gerrit.wikimedia.org/r/434710

Per T215126: PHP warning on some Echo email sending attempts due to mismatching PEAR file versions, we are actually loading the PEAR version of classes in production, even though the Composer version is included in mediawiki/vendor, causing confusion and sometimes bugs.

Note that the pear/mail files (the ones we get from composer as well) start with require_once 'PEAR.php'; require_once 'Mail/mimePart.php'; and the Debian package is the only way those requires can be fulfilled, so removing the packages will probably break email sending. This seems like a Composer bug, filed as T215224: PEAR PHP classes are loaded from system packages instead of Composer packages in WMF production.

Change 434710 had a related patch set uploaded (by Krinkle; owner: Reedy):
[operations/puppet@production] Remove pear packages from MW Application Servers

https://gerrit.wikimedia.org/r/434710

@Tgr do you see any reason not to uninstall those packages? I will for now just remove them from puppet, and uninstall them on a few selected appservers only.

Change 434710 merged by Giuseppe Lavagetto:
[operations/puppet@production] Stop installing pear packages on MW Application Servers

https://gerrit.wikimedia.org/r/434710

In T195364#5357382, @Joe wrote:

@Tgr do you see any reason not to uninstall those packages? I will for now just remove them from puppet, and uninstall them on a few selected appservers only.

In theory uninstalling should be fine now that T215224: PEAR PHP classes are loaded from system packages instead of Composer packages in WMF production has been fixed.

Mentioned in SAL (#wikimedia-operations) [2019-07-23T15:08:33Z] <_joe_> uninstalling php-pear, php-mail, php-mail-mime from mw1267 T195364

@Joe should I remove php-pear, php-mail, php-mail-mime from the rest of the fleet?