jruby warning with rack

error stack

$ bundle exec rackup -p 3003
22:47:02 - INFO - Using Guardfile at /root/calculator-widget/dev/Guardfile.
22:47:04 - INFO - Guard is using TerminalTitle to send notifications.
22:47:04 - INFO - Starting CSS Builder
22:47:04 - INFO - Building CSS
22:47:11 - INFO - Starting JS Builder
22:47:11 - INFO - Building JS
22:47:11 - INFO - Guard is now watching at '/root/'
[1] guard(main)> [2014-09-11 22:47:12] INFO  WEBrick 1.3.1
[2014-09-11 22:47:12] INFO  ruby 1.9.3 (2014-09-03) [java]
Sep 11, 2014 10:47:12 PM jnr.netdb.NativeServicesDB load
WARNING: Failed to load native services db
java.lang.RuntimeException: getservbyname_r failed
        at jnr.netdb.NativeServicesDB$LinuxServicesDB.getServiceByName(NativeServicesDB.java:220)
        at jnr.netdb.NativeServicesDB.load(NativeServicesDB.java:91)
        at jnr.netdb.Service$ServicesDBSingletonHolder.load(Service.java:122)
        at jnr.netdb.Service$ServicesDBSingletonHolder.<clinit>(Service.java:118)
        at jnr.netdb.Service.getServicesDB(Service.java:111)
        at jnr.netdb.Service.getServiceByName(Service.java:54)
        at org.jruby.ext.socket.SocketUtils.getservbyname(SocketUtils.java:107)
        at org.jruby.ext.socket.SocketUtils.buildAddrinfoList(SocketUtils.java:293)
        at org.jruby.ext.socket.SocketUtils.getaddrinfo(SocketUtils.java:191)
        at org.jruby.ext.socket.RubySocket.getaddrinfo(RubySocket.java:292)
        at org.jruby.ext.socket.RubySocket$INVOKER$s$0$4$getaddrinfo.call(RubySocket$INVOKER$s$0$4$getaddrinfo.gen)
        at org.jruby.runtime.callsite.CachingCallSite.cacheAndCall(CachingCallSite.java:296)
        at org.jruby.runtime.callsite.CachingCallSite.call(CachingCallSite.java:72)
        at org.jruby.ast.CallManyArgsNode.interpret(CallManyArgsNode.java:59)
        at org.jruby.ast.LocalAsgnNode.interpret(LocalAsgnNode.java:123)
        at org.jruby.ast.NewlineNode.interpret(NewlineNode.java:        at org.jruby.ast.BlockNode.interpret(BlockNode.java:71)
        at org.jruby.evaluator.ASTInterpreter.INTERPRET_METHOD(ASTInterpreter.java:74)
        at org.jruby.internal.runtime.methods.InterpretedMethod.call(InterpretedMethod.java:268)
        at org.jruby.internal.runtime.methods.DefaultMethod.call(DefaultMethod.java:230)
        at org.jruby.internal.runtime.methods.WrapperMethod.call(WrapperMethod.java:66)
        at org.jruby.runtime.callsite.CachingCallSite.cacheAndCall(CachingCallSite.java:366)
        at org.jruby.runtime.callsite.CachingCallSite.call(CachingCallSite.java:238)
        at org.jruby.ast.CallThreeArgNode.interpret(CallThreeArgNode.java:61)
        at org.jruby.ast.CallOneArgNode.interpret(CallOneArgNode.java:57)
        at org.jruby.ast.InstAsgnNode.interpret(InstAsgnNode.java:95)
        at org.jruby.ast.NewlineNode.interpret(NewlineNode.java:105)
        at org.jruby.evaluator.ASTInterpreter.INTERPRET_METHOD(ASTInterpreter.java:74)
        at org.jruby.internal.runtime.methods.InterpretedMethod.call(InterpretedMethod.java:225)
        at org.jruby.internal.r at org.jruby.ast.NewlineNode.interpret(NewlineNode.java:105)
        at org.jruby.ast.BlockNode.interpret(BlockNode.java:71)
        at org.jruby.evaluator.ASTInterpreter.INTERPRET_METHOD(ASTInterpreter.java:74)
        at org.jruby.internal.runtime.methods.InterpretedMethod.call(InterpretedMethod.java:247)
        at org.jruby.internal.runtime.methods.DefaultMethod.call(DefaultMethod.java:222)
        at org.jruby.runtime.callsite.SuperCallSite.cacheAndCall(SuperCallSite.java:386)
        at org.jruby.runtime.callsite.SuperCallSite.callBlock(SuperCallSite.java:238)
        at org.jruby.runtime.callsite.SuperCallSite.call(SuperCallSite.java:243)
        at org.jruby.runtime.callsite.SuperCallSite.callVarargs(SuperCallSite.java:109)
        at org.jruby.ast.SuperNode.interpret(SuperNode.java:115)
        at org.jruby.ast.NewlineNode.interpret(NewlineNode.java:105)
        at org.jruby.ast.BlockNode.interpret(BlockNode.java:71)
        at org.jruby.evaluator.ASTInterpreter.INTERPRET_METHOD(ASTInterpreter.java:74)
        at org.jruby.internal.runtime.methods.InterpretedMethod.call(Interat org.jruby.runtime.callsite.CachingCallSite.cacheAndCall(CachingCallSite.java:326)
        at org.jruby.runtime.callsite.CachingCallSite.call(CachingCallSite.java:170)
        at org.jruby.ast.CallOneArgNode.interpret(CallOneArgNode.java:57)
        at org.jruby.ast.InstAsgnNode.interpret(InstAsgnNode.java:95)
        at org.jruby.ast.NewlineNode.interpret(NewlineNode.java:105)
        at org.jruby.ast.BlockNode.interpret(BlockNode.java:71)
        at org.jruby.evaluator.ASTInterpreter.INTERPRET_METHOD(ASTInterpreter.java:74)
        at org.jruby.internal.runtime.methods.InterpretedMethod.call(InterpretedMethod.java:247)
        at org.jruby.internal.runtime.methods.DefaultMethod.call(DefaultMethod.java:222)
        at org.jruby.runtime.callsite.CachingCallSite.cacheAndCall(CachingCallSite.java:356)
        at org.jruby.runtime.callsite.CachingCallSite.callBlock(CachingCallSite.java:213)
        at org.jruby.runtime.callsite.CachingCallSite.call(CachingCallSite.java:217)
        at org.jruby.ast.CallTwoArgBlockPassNode.interpret(CallTwoArgBlockPassNode.java:62)
        at org.jruby.a  at org.jruby.ast.RootNode.interpret(RootNode.java:129)
        at org.jruby.evaluator.ASTInterpreter.INTERPRET_ROOT(ASTInterpreter.java:121)
        at org.jruby.Ruby.runInterpreter(Ruby.java:890)
        at org.jruby.Ruby.loadFile(Ruby.java:2842)
        at org.jruby.runtime.load.LibrarySearcher$ResourceLibrary.loadScript(LibrarySearcher.java:253)
        at org.jruby.runtime.load.LibrarySearcher$ResourceLibrary.load(LibrarySearcher.java:241)
        at org.jruby.runtime.load.LibrarySearcher$FoundLibrary.load(LibrarySearcher.java:50)
        at org.jruby.runtime.load.LoadService.load(LoadService.java:361)
        at org.jruby.RubyKernel.loadCommon(RubyKernel.java:1089)
        at org.jruby.RubyKernel.load19(RubyKernel.java:1081)
        at org.jruby.RubyKernel$INVOKER$s$0$1$load19.call(RubyKernel$INVOKER$s$0$1$load19.gen)
        at org.jruby.internal.runtime.methods.DynamicMethod.call(DynamicMethod.java:210)
        at org.jruby.internal.runtime.methods.DynamicMethod.call(DynamicMethod.java:206)
        at org.jruby.runtime.callsite.CachingCallSite.cacheAndCall(CachingCallSite.java:326)
        at org.jruby.runtime.callsite.CachingCallSite.call(CachingCallSite.java:170)
        at usr.local.bin.rackup.__file__(/usr/local/bin/rackup:23)
        at usr.local.bin.rackup.load(/usr/local/bin/rackup)
        at org.jruby.Ruby.runScript(Ruby.java:863)
        at org.jruby.Ruby.runScript(Ruby.java:856)
        at org.jruby.Ruby.runNormally(Ruby.java:725)
        at org.jruby.Ruby.runFromMain(Ruby.java:574)
        at org.jruby.Main.doRunFromMain(Main.java:395)
        at org.jruby.Main.internalRun(Main.java:290)
        at org.jruby.Main.run(Main.java:217)
        at org.jruby.Main.main(Main.java:197)
[2014-09-11 22:47:12] INFO  WEBrick::HTTPServer#start: pid=84 port=3003

• JRuby version 1.7.15
• Debian wheezy and Ubuntu 12.04.5 in a Docker container.
• openjdk-6-jre and openjdk-7-jre