Although there was a fix for this bug from version 1.14-4 to 1.14-5 the bug described in JENKINS-24145 still occurs on my system:

Error while serving http://(myJenkins)/ghprbhook/
java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
...
at org.kohsuke.stapler.Function$InstanceFunction.invoke(Function.java:298)
at org.kohsuke.stapler.Function.bindAndInvoke(Function.java:161)
at org.kohsuke.stapler.Function.bindAndInvokeAndServeResponse(Function.java:96)
...
at org.kohsuke.stapler.Stapler.service(Stapler.java:225)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:848)
at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:686)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1494)
at hudson.util.PluginServletFilter$1.doFilter(PluginServletFilter.java:96)
at hudson.plugins.greenballs.GreenBallFilter.doFilter(GreenBallFilter.java:58)
...
at hudson.security.HudsonFilter.doFilter(HudsonFilter.java:164)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1482)
at org.kohsuke.stapler.compression.CompressionFilter.doFilter(CompressionFilter.java:46)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1482)
...
at java.lang.Thread.run(Thread.java:722)
Caused by: java.lang.Error: java.io.FileNotFoundException: http://(myGitHubEnterprise)/api/v3/api/v3/repos/(myOrg)/(myProject)/pulls/4/commits
at org.kohsuke.github.Requester$1.fetch(Requester.java:304)
at org.kohsuke.github.Requester$1.hasNext(Requester.java:271)
at org.kohsuke.github.PagedIterator.fetch(PagedIterator.java:44)
at org.kohsuke.github.PagedIterator.hasNext(PagedIterator.java:32)
at org.jenkinsci.plugins.ghprb.GhprbPullRequest.tryBuild(GhprbPullRequest.java:220)
at org.jenkinsci.plugins.ghprb.GhprbPullRequest.check(GhprbPullRequest.java:174)
at org.jenkinsci.plugins.ghprb.GhprbRepository.onIssueCommentHook(GhprbRepository.java:214)
at org.jenkinsci.plugins.ghprb.GhprbRootAction.doIndex(GhprbRootAction.java:58)
... 73 more
Caused by: java.io.FileNotFoundException: http://(myGitHubEnterprise)/api/v3/api/v3/repos/(myOrg)/(myProject)/pulls/4/commits
at sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1623)
at org.kohsuke.github.Requester.parse(Requester.java:359)
at org.kohsuke.github.Requester.access$300(Requester.java:59)
at org.kohsuke.github.Requester$1.fetch(Requester.java:295)
... 80 more