Steps to reproduce:

1. Install Foreman 1.2 Nightly on RHEL6 (Sat6/Katello not required)
2. Attempt to save hostgroup
3. See "Stack Level Too Deep" exception on saving hostgroup
4. Bug is impervious to server change (webrick or passenger), db changes (sqlite or postgres) and rails upgrades (3.2.8 -> 3.2.12)
5. Bug is NOT reproducable on a gem install, ie outside of SCL

gemset:
[root@balon ~]# scl enable ruby193 "gem list"

*** LOCAL GEMS ***
actionmailer (3.2.8)
actionpack (3.2.8)
activemodel (3.2.8)
activerecord (3.2.8)
activeresource (3.2.8)
activesupport (3.2.8)
ancestry (1.3.0)
apipie-rails (0.0.18)
arel (3.0.2)
audited (3.0.0)
audited-activerecord (3.0.0)
bigdecimal (1.1.0)
builder (3.0.0)
bundler (1.1.4)
bundler_ext (0.3.0)
coffee-rails (3.2.2)
coffee-script (2.2.0)
coffee-script-source (1.3.3)
daemons (1.1.4)
diff-lcs (1.1.3)
erubis (2.7.0)
eventmachine (0.12.10)
execjs (1.4.0)
fast_gettext (0.5.10)
file-tail (1.0.5)
gettext_i18n_rails (0.2.13)
hike (1.2.1)
i18n (0.6.0)
i18n_data (0.2.7)
io-console (0.3)
journey (1.0.4)
jquery-rails (2.0.2)
jquery-ui-rails (4.0.2)
json (1.5.4)
mail (2.4.4)
mime-types (1.19)
multi_json (1.3.6)
net-http-persistent (2.7)
net-ldap (0.2.2)
oauth (0.4.7)
passenger (3.0.17)
pg (0.12.2)
polyglot (0.3.3)
rabl (0.7.6)
rack (1.4.1)
rack-cache (1.2)
rack-ssl (1.3.2)
rack-test (0.6.1)
rails (3.2.8)
railties (3.2.8)
rake (0.9.2.2)
rdoc (3.12)
ref (1.0.0)
rest-client (1.6.1)
ruby2ruby (2.0.1)
ruby_parser (3.1.1)
safemode (1.2.0)
sass (3.1.20)
sass-rails (3.2.5)
scoped_search (2.5.1)
sexp_processor (4.1.3)
sprockets (2.4.5)
spruz (0.2.5)
sqlite3 (1.3.6)
therubyracer (0.11.0beta5)
thin (1.3.1)
thor (0.15.4)
tilt (1.3.3)
treetop (1.4.10)
twitter-bootstrap-rails (2.2.6)
tzinfo (0.3.33)
uglifier (1.2.6)
uuidtools (2.1.3)
will_paginate (3.0.2)

stack:
   #0 [block]   rescue in rollback_active_record_state! <ActiveRecord::Transactions#rollback_active_recor
   #1 [method]  save <ActiveRecord::Transactions#save(*arg1)>
   #2 [method]  insert_record <ActiveRecord::Associations::HasManyAssociation#insert_record(record, valid
   #3 [block]   block (2 levels) in create_record <ActiveRecord::Associations::CollectionAssociation#crea
   #4 [method]  add_to_target <ActiveRecord::Associations::CollectionAssociation#add_to_target(record)>
   #5 [block]   block in create_record <ActiveRecord::Associations::CollectionAssociation#create_record(a
   #6 [block]   block in transaction <ActiveRecord::Associations::CollectionAssociation#transaction(*args
   #7 [method]  transaction <ActiveRecord::ConnectionAdapters::DatabaseStatements#transaction(options=?)>
   #8 [method]  transaction <ActiveRecord::Transactions::ClassMethods#transaction(options=?, &block)>
   #9 [method]  transaction <ActiveRecord::Associations::CollectionAssociation#transaction(*args)>
   #10 [method]  create_record <ActiveRecord::Associations::CollectionAssociation#create_record(attribute
   #11 [method]  create <ActiveRecord::Associations::CollectionAssociation#create(attributes=?, options=?
   #12 [method]  create <Array#inspect()>
   #13 [block]   block in write_audit <Audited::Auditor::AuditedInstanceMethods#write_audit(attrs)>
   #14 [method]  _run__1810368630087873722__audit__709258232627691241__callbacks <Hostgroup#_run__1810368
   #15 [method]  __run_callback <ActiveSupport::Callbacks::ClassMethods#__run_callback(key, kind, object,
   #16 [method]  _run_audit_callbacks <Hostgroup#_run_audit_callbacks(key=?, &blk)>
   #17 [method]  run_callbacks <ActiveSupport::Callbacks#run_callbacks(kind, *args, &block)>
   #18 [method]  write_audit <Audited::Auditor::AuditedInstanceMethods#write_audit(attrs)>
   #19 [method]  audit_create <Audited::Auditor::AuditedInstanceMethods#audit_create()>
   #20 [method]  _run__1810368630087873722__create__709258232627691241__callbacks <Hostgroup#_run__181036
   #21 [method]  __run_callback <ActiveSupport::Callbacks::ClassMethods#__run_callback(key, kind, object,
   #22 [method]  _run_create_callbacks <ActiveRecord::Base#_run_create_callbacks(key=?, &blk)>
   #23 [method]  run_callbacks <ActiveSupport::Callbacks#run_callbacks(kind, *args, &block)>
   #24 [method]  create <ActiveRecord::Callbacks#create()>
   #25 [method]  create_or_update <ActiveRecord::Persistence#create_or_update()>
   #26 [block]   block in create_or_update <ActiveRecord::Callbacks#create_or_update()>
   #27 [method]  _run__1810368630087873722__save__709258232627691241__callbacks <Hostgroup#_run__18103686
   #28 [method]  __run_callback <ActiveSupport::Callbacks::ClassMethods#__run_callback(key, kind, object,
   #29 [method]  _run_save_callbacks <ActiveRecord::Base#_run_save_callbacks(key=?, &blk)>
   #30 [method]  run_callbacks <ActiveSupport::Callbacks#run_callbacks(kind, *args, &block)>
   #31 [method]  create_or_update <ActiveRecord::Callbacks#create_or_update()>
   #32 [method]  save <ActiveRecord::Persistence#save(*arg1)>
   #33 [method]  save <ActiveRecord::Validations#save(options=?)>
   #34 [method]  save <ActiveRecord::AttributeMethods::Dirty#save(*arg1)>
   #35 [block]   block (2 levels) in save <ActiveRecord::Transactions#save(*arg1)>
   #36 [block]   block in with_transaction_returning_status <ActiveRecord::Transactions#with_transaction_
   #37 [method]  transaction <ActiveRecord::ConnectionAdapters::DatabaseStatements#transaction(options=?)
   #38 [method]  transaction <ActiveRecord::Transactions::ClassMethods#transaction(options=?, &block)>
   #39 [method]  with_transaction_returning_status <ActiveRecord::Transactions#with_transaction_returning
   #40 [block]   block in save <ActiveRecord::Transactions#save(*arg1)>
   #41 [method]  rollback_active_record_state! <ActiveRecord::Transactions#rollback_active_record_state!(
   #42 [method]  save <ActiveRecord::Transactions#save(*arg1)>
=> #43 [method]  create <HostgroupsController#create()>