Continuous integration setup using bitcoind regtest on travis-ci Subtitle: travis-ci fails to run generate JSON-RPC method on regtest

I'm trying to setup CI process on https://travis-ci.org platform to install bitcoind and start new blockchain using regtest mode.
I want to do this to run unit tests of my applications which uses wallet data. Methods against bitcoind are working fine except the generate method which is needed to mine some bitcoins in regtest private chain.  

It looks like some bitcoind/travis-ci related issue.  


generate method is working fine in my local CI process (non-travis).
Travis-CI is working fine if I comment the generate method call in CI tests.  


generate method call when using travis-ci fails with the following error:



{"code":-32601,"message":"Method not found"}


bitcoin.conf:  

server=1
regtest=1
gen=1
rpcuser=someuser
rpcpassword=somepass


.travis.yml:

language: r
sudo: required

before_script:
  - sudo apt-add-repository ppa:bitcoin/bitcoin -y
  - sudo apt-get update -qq
  - sudo apt-get install bitcoind -y

r_github_packages:
 - jangorecki/rbitcoind

after_script:
 - cat $(find . -maxdepth 1 -name "*.Rcheck" -type d)/tests/tests.Rout


Is there any trick in setup I should use to make travis-ci capable to run CI on regtest chain, including generate method?  

Leaving the build links just for reference:
- generate method commented - CI passed: https://travis-ci.org/jangorecki/rpc.generate/builds/77207297
- use generate - CI failed: https://travis-ci.org/jangorecki/rpc.generate/builds/77208666
v0.11.0 and after:

Check and make sure that your daemon version is v0.11.0 or greater. If it is, the generate method should work.

Pre v0.11.0:

The setgenerate true method should be used.

In a standard network (such as testnet or main), setgenerate true will turn mining on indefinitely. In regtest, it just mines one block. You can also do 

setgenerate(TRUE, 10)


To mine 10 regtest blocks. The second parameter is called the generation limit.