I have this file too, but obviously the gem are not installed
root@ubuntu-app:/var/www/discourse# gem list
*** LOCAL GEMS ***
bigdecimal (1.2.8)
bundler (1.14.5, 1.13.7)
did_you_mean (1.0.0)
io-console (0.4.5)
json (1.8.3)
minitest (5.8.5)
net-telnet (0.1.1)
power_assert (0.2.6)
psych (2.1.0)
rake (10.4.2)
rdoc (4.2.1)
test-unit (3.1.5)
This is a fresh install, the lastest version of discourse downloaded this morning.