Guard against fork being unavailable
Guard against fork being unavailable

Now the tests pass on all platforms on Travis.

pombredanne/capybara,jarib/capybara,gonzedge/capybara,randoum/capybara,DariaKalynovska/capybara,gonzedge/capybara,twalpole/capybara,y-yagi/capybara,teamcapybara/capybara,shepmaster/capybara,ksmaheshkumar/capybara,sideci-sample/sideci-sample-capybara,y-yagi/capybara,teamcapybara/capybara,olivierlacan/capybara,irfanah/capybara,mreinsch/capybara,mohanraj1311/capybara,wenbofantasy/capybara,jnicklas/capybara,benlovell/capybara,jnicklas/capybara,tjouan/capybara,teamcapybara/capybara,pombredanne/capybara,mreinsch/capybara,ngpestelos/capybara,randoum/capybara,Bartuz/capybara,tjouan/capybara,ngpestelos/capybara,ksmaheshkumar/capybara,jillianrosile/capybara,mlarraz/capybara,mohanraj1311/capybara,mlarraz/capybara,shepmaster/capybara,ducthanh/capybara,soutaro/capybara,olivierlacan/capybara,jillianrosile/capybara,irfanah/capybara,jnicklas/capybara,tjgrathwell/capybara,shepmaster/capybara,khaidpham/capybara,ducthanh/capybara,khaidpham/capybara,twalpole/capybara,ngpestelos/capybara,ducthanh/capybara,mohanraj1311/capybara,mlarraz/capybara,irfanah/capybara,tjgrathwell/capybara,Bartuz/capybara,gonzedge/capybara,ksmaheshkumar/capybara,benlovell/capybara,jarib/capybara,Bartuz/capybara,twalpole/capybara,sideci-sample/sideci-sample-capybara,soutaro/capybara,pombredanne/capybara,olivierlacan/capybara,randoum/capybara,DariaKalynovska/capybara,khaidpham/capybara,soutaro/capybara,DariaKalynovska/capybara,tjgrathwell/capybara,jillianrosile/capybara,wenbofantasy/capybara,y-yagi/capybara,tjouan/capybara