The same error also occurs in the /var/lib/dpkg/info/monotone-server.postinst . By altering the shebang of both files from #!/bin/sh to #!/bin/bash, installation runs without problem.
The same error also occurs in the /var/lib/ dpkg/info/ monotone- server. postinst . By altering the shebang of both files from #!/bin/sh to #!/bin/bash, installation runs without problem.