3.141 Install/upgrade fails with error "newline unexpected"

Issue

(On Ubuntu 16.04.3 using the debian package at https://debian.aegirproject.org)

Either a clean install of aegir 7.x-3.141 or an upgrade from 7.x-3.130 to 7.x-3.141 fails with same error messages:

$ sudo apt-get install aegir3
...
Setting up aegir3-hostmaster (3.141) ...
/usr/local/bin/drush: 2: /usr/local/bin/drush: Syntax error: newline unexpected
dpkg: error processing package aegir3-hostmaster (--configure):
 subprocess installed post-installation script returned error exit status 2
dpkg: dependency problems prevent configuration of aegir3:
 aegir3 depends on aegir3-hostmaster (>= 3.141); however:
  Package aegir3-hostmaster is not configured yet.

dpkg: error processing package aegir3 (--configure):
 dependency problems - leaving unconfigured
...
Errors were encountered while processing:
 aegir3-hostmaster
 aegir3
E: Sub-process /usr/bin/dpkg returned an error code (1)

Environment

Ubuntu 16.04.3 LTS
Kernel 4.4.0-112-generic #135-Ubuntu SMP Fri Jan 19 11:48:36 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux
php7.0-common:amd64/xenial-security 7.0.22-0ubuntu0.16.04.1 uptodate
mysql-server:all/xenial-security 5.7.21-0ubuntu0.16.04.1 uptodate
mysql-client-5.7:amd64/xenial-security 5.7.21-0ubuntu0.16.04.1 uptodate
apache2:amd64/xenial-security 2.4.18-2ubuntu3.5 uptodate