Foreman-installer error

Problem:
Not able to run foreman-installer. Running foreman-installer fails with this error:

[root@foremanserver ~]# foreman-installer 
/usr/share/rubygems/rubygems/specification.rb:2032:in `raise_if_conflicts': Unable to activate kafo-2.0.0, because highline-1.6.19 conflicts with highline (< 2.0, >= 1.6.21) (Gem::LoadError)
	from /usr/share/rubygems/rubygems/specification.rb:1178:in `activate'
	from /usr/share/rubygems/rubygems.rb:186:in `rescue in try_activate'
	from /usr/share/rubygems/rubygems.rb:183:in `try_activate'
	from /usr/share/rubygems/rubygems/core_ext/kernel_require.rb:132:in `rescue in require'
	from /usr/share/rubygems/rubygems/core_ext/kernel_require.rb:144:in `require'
	from /sbin/foreman-installer:3:in `<main>'


[root@foremanserver ~]# rpm -qa | grep foreman
foreman-release-scl-3-1.el7.noarch
foreman-1.15.6-1.el7.noarch
foreman-release-1.15.6-1.el7.noarch
tfm-rubygem-hammer_cli_foreman-0.10.2-1.el7.noarch
tfm-rubygem-foreman-tasks-core-0.1.8-1.fm1_15.el7.noarch
tfm-rubygem-foreman-tasks-0.9.6-1.fm1_15.el7.noarch
tfm-rubygem-foreman_remote_execution-1.3.7-1.fm1_15.el7.noarch
foreman-postgresql-1.15.6-1.el7.noarch
foreman-proxy-1.15.6-1.el7.noarch
tfm-rubygem-foreman_userdata-0.0.1-2.fm1_17.el7.noarch
tfm-rubygem-foreman_setup-5.0.0-1.fm1_13.el7.noarch
foreman-vmware-1.15.6-1.el7.noarch
foreman-cli-1.15.6-1.el7.noarch
tfm-rubygem-foreman_remote_execution_core-1.0.6-1.fm1_15.el7.noarch
foreman-selinux-1.15.6-1.el7.noarch
foreman-installer-1.15.6-2.el7.noarch
foreman-debug-1.15.6-1.el7.noarch
[root@foremanserver ~]# 


[root@foremanserver ~]# gem list

*** LOCAL GEMS ***

addressable (2.4.0)
ansi (1.4.3)
apipie-bindings (0.1.0)
awesome_print (1.7.0, 1.0.2)
bigdecimal (1.2.0)
bolt (0.13.0)
builder (3.2.3)
bundler (1.7.8)
bundler_ext (0.4.1)
CFPropertyList (2.3.6)
clamp (1.0.0)
concurrent-ruby (1.0.3)
daemon_controller (1.1.2)
erubis (2.7.0)
facter (2.4.6)
facterdb (0.3.10)
fast_gettext (1.1.0, 1.0.0)
fastercsv (1.5.4)
ffi (1.9.10)
gettext (3.2.2)
gettext-setup (0.24)
gssapi (1.2.0, 1.1.2)
gyoku (1.3.1)
hashie (2.0.5)
hiera (3.3.1)
hiera-eyaml (2.1.0)
highline (1.6.19)
httpclient (2.8.3)
io-console (0.4.2)
jgrep (1.4.1)
json (1.7.7)
json_pure (1.8.6)
kafo (2.0.0)
kafo_parsers (0.1.6)
kafo_wizards (0.0.1)
little-plugger (1.1.3)
locale (2.1.2, 2.0.9)
logging (1.8.2)
mime-types (1.19)
minitar (0.6.1)
multi_json (1.10.1)
net-http-persistent (2.8)
net-scp (1.2.1)
net-ssh (4.2.0)
netrc (0.7.7)
nori (2.6.0)
oauth (0.5.1)
orchestrator_client (0.2.2)
powerbar (1.0.17)
psych (2.0.0)
puppet (4.10.1)
rack (1.6.4)
rack-protection (1.5.3)
rake (0.9.6)
rb-inotify (0.9.7)
rb-readline (0.5.1)
rdoc (4.0.0)
rest-client (1.6.7)
rkerberos (0.1.3)
rubyipmi (0.10.0)
rubyntlm (0.6.2)
rubyzip (1.2.1)
sinatra (1.4.8)
smart_proxy_dynflow (0.1.8)
smart_proxy_remote_execution_ssh (0.1.6)
stomp (1.3.2)
table_print (1.5.1)
terminal-table (1.8.0)
text (1.3.1)
thor (0.19.1)
tilt (2.0.7)
trollop (2.1.2)
unicode-display_width (1.3.0)
win32-dir (0.4.9)
win32-process (0.7.5)
win32-security (0.2.5)
win32-service (0.8.8)
winrm (2.2.3)
winrm-fs (1.1.1)
[root@foremanserver ~]#

Expected outcome:
foreman-installer should work without any error.

Foreman and Proxy versions:

[root@foremanserver ~]# rpm -qa | grep foreman
foreman-release-scl-3-1.el7.noarch
foreman-1.15.6-1.el7.noarch
foreman-release-1.15.6-1.el7.noarch
tfm-rubygem-hammer_cli_foreman-0.10.2-1.el7.noarch
tfm-rubygem-foreman-tasks-core-0.1.8-1.fm1_15.el7.noarch
tfm-rubygem-foreman-tasks-0.9.6-1.fm1_15.el7.noarch
tfm-rubygem-foreman_remote_execution-1.3.7-1.fm1_15.el7.noarch
foreman-postgresql-1.15.6-1.el7.noarch
foreman-proxy-1.15.6-1.el7.noarch
tfm-rubygem-foreman_userdata-0.0.1-2.fm1_17.el7.noarch
tfm-rubygem-foreman_setup-5.0.0-1.fm1_13.el7.noarch
foreman-vmware-1.15.6-1.el7.noarch
foreman-cli-1.15.6-1.el7.noarch
tfm-rubygem-foreman_remote_execution_core-1.0.6-1.fm1_15.el7.noarch
foreman-selinux-1.15.6-1.el7.noarch
foreman-installer-1.15.6-2.el7.noarch
foreman-debug-1.15.6-1.el7.noarch
[root@foremanserver ~]# 

Foreman and Proxy plugin versions:

Other relevant data:
As per IRC conversation with @ekohl I did gem clean highline but that didn’t help to fix the issue.

Any input is appreciated.