pyclean is part of python-minimal... Do you perhaps have some manual python installation that removed /usr/bin/pyclean? Or are you running with a PATH that doesn't include /usr/bin or something equivalently crazy?
Or at the very least, please check if you have /usr/bin/pyclean and it works. ** Changed in: libxml2 (Ubuntu) Status: New => Incomplete -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to libxml2 in Ubuntu. https://bugs.launchpad.net/bugs/1736858 Title: package python-libxml2 2.9.4+dfsg1-2.2ubuntu0.1 failed to install/upgrade: subprocess new pre-removal script returned error exit status 127 Status in libxml2 package in Ubuntu: Incomplete Bug description: can't install it ProblemType: Package DistroRelease: Ubuntu 17.04 Package: python-libxml2 2.9.4+dfsg1-2.2ubuntu0.1 ProcVersionSignature: Ubuntu 4.10.0-40.44-generic 4.10.17 Uname: Linux 4.10.0-40-generic x86_64 NonfreeKernelModules: nvidia_modeset nvidia ApportVersion: 2.20.4-0ubuntu4.8 Architecture: amd64 Date: Thu Dec 7 12:47:53 2017 ErrorMessage: subprocess new pre-removal script returned error exit status 127 InstallationDate: Installed on 2017-12-03 (3 days ago) InstallationMedia: Ubuntu-Kylin 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.1) RelatedPackageVersions: dpkg 1.18.10ubuntu2 apt 1.4.6~17.04.1 SourcePackage: libxml2 Title: package python-libxml2 2.9.4+dfsg1-2.2ubuntu0.1 failed to install/upgrade: subprocess new pre-removal script returned error exit status 127 UpgradeStatus: Upgraded to zesty on 2017-12-04 (2 days ago) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/libxml2/+bug/1736858/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp