Allow jruby 18 failure.

I'm getting a weird error from Jruby:

$ script/ci.sh
81CachingCallSite.java:311:in `cacheAndCall': java.lang.NullPointerException
82	from CachingCallSite.java:169:in `call'
83	from /home/vagrant/.rvm/rubies/jruby-1.6.7.2/lib/ruby/site_ruby/1.8/rubygems/version.rb:279:in `__file__'
84	from /home/vagrant/.rvm/rubies/jruby-1.6.7.2/lib/ruby/site_ruby/1.8/rubygems/version.rb:-1:in `__file__'
85	from JittedMethod.java:127:in `call'
86	from DefaultMethod.java:183:in `call'
87	from CachingCallSite.java:133:in `call'
88	from CallNoArgNode.java:63:in `interpret'
89	from LocalAsgnNode.java:123:in `interpret'
90	from NewlineNode.java:104:in `interpret'
91	from BlockNode.java:71:in `interpret'
92	from ASTInterpreter.java:74:in `INTERPRET_METHOD'
93	from InterpretedMethod.java:190:in `call'
94	from DefaultMethod.java:199:in `call'
95	from RuntimeHelpers.java:2622:in `invokedynamic'
96	from RubyComparable.java:149:in `op_ge'
97	from RubyComparable$s$1$0$op_ge.gen:65535:in `call'
98	from CachingCallSite.java:312:in `cacheAndCall'
99	from CachingCallSite.java:169:in `call'
100	from GeCallSite.java:37:in `call'
101	from CallOneArgNode.java:57:in `interpret'
102	from IfNode.java:111:in `interpret'
103	from NewlineNode.java:104:in `interpret'
104	from BlockNode.java:71:in `interpret'
105	from IfNode.java:117:in `interpret'
106	from NewlineNode.java:104:in `interpret'
107	from BlockNode.java:71:in `interpret'
108	from ASTInterpreter.java:111:in `INTERPRET_BLOCK'
109	from InterpretedBlock.java:374:in `evalBlockBody'
110	from InterpretedBlock.java:347:in `yield'
111	from InterpretedBlock.java:304:in `yield'
112	from Block.java:130:in `yield'
113	from YieldNode.java:119:in `interpret'
114	from IfNode.java:117:in `interpret'
115	from NewlineNode.java:104:in `interpret'
116	from BlockNode.java:71:in `interpret'
117	from ASTInterpreter.java:74:in `INTERPRET_METHOD'
118	from InterpretedMethod.java:169:in `call'
119	from DefaultMethod.java:191:in `call'
120	from CachingCallSite.java:142:in `callBlock'
121	from CachingCallSite.java:148:in `call'
122	from RubyClass.java:822:in `newInstance'
123	from RubyClass$i$newInstance.gen:65535:in `call'
124	from CachingCallSite.java:302:in `cacheAndCall'
125	from CachingCallSite.java:144:in `callBlock'
126	from CachingCallSite.java:153:in `callIter'
127	from CallNoArgBlockNode.java:64:in `interpret'
128	from NewlineNode.java:104:in `interpret'
129	from RootNode.java:129:in `interpret'
130	from ASTInterpreter.java:95:in `INTERPRET_EVAL'
131	from ASTInterpreter.java:166:in `evalWithBinding'
132	from RubyKernel.java:1126:in `evalCommon'
133	from RubyKernel.java:1083:in `eval'
134	from RubyKernel$s$0$3$eval.gen:65535:in `call'
135	from DynamicMethod.java:227:in `call'
136	from DynamicMethod.java:223:in `call'
137	from CachingCallSite.java:235:in `call'
138	from FCallThreeArgNode.java:40:in `interpret'
139	from LocalAsgnNode.java:123:in `interpret'
140	from NewlineNode.java:104:in `interpret'
141	from BlockNode.java:71:in `interpret'
142	from RescueNode.java:216:in `executeBody'
143	from RescueNode.java:120:in `interpretWithJavaExceptions'
144	from RescueNode.java:110:in `interpret'
145	from BeginNode.java:83:in `interpret'
146	from NewlineNode.java:104:in `interpret'
147	from BlockNode.java:71:in `interpret'
148	from ASTInterpreter.java:74:in `INTERPRET_METHOD'
149	from InterpretedMethod.java:190:in `call'
150	from DefaultMethod.java:199:in `call'
151	from CachingCallSite.java:167:in `call'
152	from CallOneArgNode.java:57:in `interpret'
153	from DAsgnNode.java:110:in `interpret'
154	from NewlineNode.java:104:in `interpret'
155	from BlockNode.java:71:in `interpret'
156	from ASTInterpreter.java:111:in `INTERPRET_BLOCK'
157	from InterpretedBlock.java:374:in `evalBlockBody'
158	from InterpretedBlock.java:347:in `yield'
159	from InterpretedBlock.java:304:in `yield'
160	from Block.java:130:in `yield'
161	from RubyArray.java:1608:in `eachCommon'
162	from RubyArray.java:1615:in `each'
163	from RubyArray$i$0$0$each.gen:65535:in `call'
164	from CachingCallSite.java:302:in `cacheAndCall'
165	from CachingCallSite.java:144:in `callBlock'
166	from CachingCallSite.java:153:in `callIter'
167	from CallNoArgBlockNode.java:64:in `interpret'
168	from NewlineNode.java:104:in `interpret'
169	from ASTInterpreter.java:111:in `INTERPRET_BLOCK'
170	from InterpretedBlock.java:374:in `evalBlockBody'
171	from InterpretedBlock.java:347:in `yield'
172	from InterpretedBlock.java:304:in `yield'
173	from Block.java:130:in `yield'
174	from RubyArray.java:1608:in `eachCommon'
175	from RubyArray.java:1615:in `each'
176	from RubyArray$i$0$0$each.gen:65535:in `call'
177	from CachingCallSite.java:302:in `cacheAndCall'
178	from CachingCallSite.java:144:in `callBlock'
179	from CachingCallSite.java:153:in `callIter'
180	from CallNoArgBlockNode.java:64:in `interpret'
181	from NewlineNode.java:104:in `interpret'
182	from BlockNode.java:71:in `interpret'
183	from IfNode.java:119:in `interpret'
184	from NewlineNode.java:104:in `interpret'
185	from BlockNode.java:71:in `interpret'
186	from ASTInterpreter.java:74:in `INTERPRET_METHOD'
187	from InterpretedMethod.java:147:in `call'
188	from DefaultMethod.java:183:in `call'
189	from CachingCallSite.java:292:in `cacheAndCall'
190	from CachingCallSite.java:135:in `call'
191	from CallNoArgNode.java:63:in `interpret'
192	from CallNoArgBlockNode.java:60:in `interpret'
193	from NewlineNode.java:104:in `interpret'
194	from BlockNode.java:71:in `interpret'
195	from ASTInterpreter.java:74:in `INTERPRET_METHOD'
196	from InterpretedMethod.java:169:in `call'
197	from DefaultMethod.java:191:in `call'
198	from RubyClass.java:552:in `finvoke'
199	from RuntimeHelpers.java:529:in `invoke'
200	from RubyEnumerable.java:93:in `callEach'
201	from RubyEnumerable.java:650:in `selectCommon'
202	from RubyEnumerable.java:672:in `find_all'
203	from RubyEnumerable$s$0$0$find_all.gen:65535:in `call'
204	from CachingCallSite.java:302:in `cacheAndCall'
205	from CachingCallSite.java:144:in `callBlock'
206	from CachingCallSite.java:153:in `callIter'
207	from CallNoArgBlockNode.java:64:in `interpret'
208	from LocalAsgnNode.java:123:in `interpret'
209	from NewlineNode.java:104:in `interpret'
210	from BlockNode.java:71:in `interpret'
211	from ASTInterpreter.java:74:in `INTERPRET_METHOD'
212	from InterpretedMethod.java:190:in `call'
213	from DefaultMethod.java:199:in `call'
214	from CachingCallSite.java:312:in `cacheAndCall'
215	from CachingCallSite.java:169:in `call'
216	from FCallOneArgNode.java:36:in `interpret'
217	from LocalAsgnNode.java:123:in `interpret'
218	from NewlineNode.java:104:in `interpret'
219	from BlockNode.java:71:in `interpret'
220	from ASTInterpreter.java:74:in `INTERPRET_METHOD'
221	from InterpretedMethod.java:147:in `call'
222	from DefaultMethod.java:183:in `call'
223	from CachingCallSite.java:292:in `cacheAndCall'
224	from CachingCallSite.java:135:in `call'
225	from CallNoArgNode.java:63:in `interpret'
226	from LocalAsgnNode.java:123:in `interpret'
227	from NewlineNode.java:104:in `interpret'
228	from BlockNode.java:71:in `interpret'
229	from ASTInterpreter.java:74:in `INTERPRET_METHOD'
230	from InterpretedMethod.java:147:in `call'
231	from DefaultMethod.java:183:in `call'
232	from CachingCallSite.java:292:in `cacheAndCall'
233	from CachingCallSite.java:135:in `call'
234	from CallNoArgNode.java:63:in `interpret'
235	from LocalAsgnNode.java:123:in `interpret'
236	from NewlineNode.java:104:in `interpret'
237	from BlockNode.java:71:in `interpret'
238	from ASTInterpreter.java:74:in `INTERPRET_METHOD'
239	from InterpretedMethod.java:233:in `call'
240	from DefaultMethod.java:215:in `call'
241	from CachingCallSite.java:332:in `cacheAndCall'
242	from CachingCallSite.java:203:in `call'
243	from /home/vagrant/.rvm/gems/jruby-1.6.7.2@global/bin/bundle:22:in `__file__'
244	from /home/vagrant/.rvm/gems/jruby-1.6.7.2@global/bin/bundle:-1:in `load'
245	from Ruby.java:697:in `runScript'
246	from Ruby.java:690:in `runScript'
247	from Ruby.java:597:in `runNormally'
248	from Ruby.java:446:in `runFromMain'
249	from Main.java:369:in `doRunFromMain'
250	from Main.java:258:in `internalRun'
251	from Main.java:224:in `run'
252	from Main.java:208:in `run'
253	from Main.java:188:in `main'
254
255Done. Build script exited with: 1