package emma 0.5-2 failed to install/upgrade: new emma package pre-installation script subprocess returned error exit status 127

[Neven Falica]

Tried to run `sudo dpkg -i <emma package file name>`, at first failed because I had no `python-mysqldb` package, then after adding missing package, failed again with text:

```
Preparing to unpack .../archives/emma_0.6-5_all.deb ...
/var/lib/dpkg/tmp.ci/preinst: 6: /var/lib/dpkg/tmp.ci/preinst: pycentral: not found
dpkg: error processing archive /var/cache/apt/archives/emma_0.6-5_all.deb (--unpack):
 new emma package pre-installation script subprocess returned error exit status 127
Errors were encountered while processing:
 /var/cache/apt/archives/emma_0.6-5_all.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)
```

ProblemType: Package
DistroRelease: Ubuntu 18.04
Package: emma 0.5-2
ProcVersionSignature: Ubuntu 4.15.0-22.24-generic 4.15.17
Uname: Linux 4.15.0-22-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.1
AptOrdering:
 libmysqlclient20:amd64: Install
 python-mysqldb:amd64: Install
 emma:amd64: Install
 NULL: ConfigurePending
Architecture: amd64
Date: Thu Jun 7 14:51:17 2018
ErrorMessage: new emma package pre-installation script subprocess returned error exit status 127
InstallationDate: Installed on 2018-06-07 (0 days ago)
InstallationMedia: Xubuntu 18.04 LTS "Bionic Beaver" - Release amd64 (20180426)
PackageArchitecture: all
Python3Details: /usr/bin/python3.6, Python 3.6.5, python3-minimal, 3.6.5-3
PythonDetails: /usr/bin/python2.7, Python 2.7.15rc1, python-minimal, 2.7.15~rc1-1
RelatedPackageVersions:
 dpkg 1.19.0.5ubuntu2
 apt 1.6.1
SourcePackage: emma
Title: package emma 0.5-2 failed to install/upgrade: new emma package pre-installation script subprocess returned error exit status 127
UpgradeStatus: No upgrade log present (probably fresh install)