500 for EmptyPullRequest

Attempt to create PullRequest between similar branches (master and master-test) сauses EmptyPullRequestException and user see 500 HTTP response.
Seems error handler with description should be here.

2014-12-16 19:11:43 "POST /projects/STASH/repos/stash-plugins/pull-requests HTTP/1.0" c.a.s.i.w.pull.PullRequestController Exception occurred
com.atlassian.stash.pull.EmptyPullRequestException: Branch "master" is already up-to-date with branch "master-test" in repository "stash-plugins".
at com.atlassian.stash.internal.pull.PullRequestServiceImpl.checkHasChangesets(PullRequestServiceImpl.java:1060) ~[PullRequestServiceImpl.class:na]
at com.atlassian.stash.internal.pull.PullRequestServiceImpl.create(PullRequestServiceImpl.java:389) ~[PullRequestServiceImpl.class:na]
at com.atlassian.stash.internal.pull.PullRequestServiceImpl.create(PullRequestServiceImpl.java:86) ~[PullRequestServiceImpl.class:na]
at com.atlassian.stash.internal.web.pull.PullRequestController.createPullRequest(PullRequestController.java:148) ~[PullRequestController.class:na]
at com.atlassian.applinks.core.rest.context.ContextFilter.doFilter(ContextFilter.java:25) [applinks-plugin-4.3.5_1414620380000.jar:na]
at com.atlassian.stash.internal.spring.security.StashAuthenticationFilter.doFilter(StashAuthenticationFilter.java:86) [StashAuthenticationFilter.class:na]
at com.atlassian.stash.internal.web.auth.BeforeLoginPluginAuthenticationFilter.doInsideSpringSecurityChain(BeforeLoginPluginAuthenticationFilter.java:111) [BeforeLoginPluginAuthenticationFilter.class:na]
at com.atlassian.stash.internal.web.auth.BeforeLoginPluginAuthenticationFilter.doFilter(BeforeLoginPluginAuthenticationFilter.java:77) [BeforeLoginPluginAuthenticationFilter.class:na]
at com.atlassian.security.auth.trustedapps.filter.TrustedApplicationsFilter.doFilter(TrustedApplicationsFilter.java:100) [TrustedApplicationsFilter.class:na]
at com.atlassian.oauth.serviceprovider.internal.servlet.OAuthFilter.doFilter(OAuthFilter.java:79) [atlassian-oauth-service-provider-plugin-1.9.9_1415929402000.jar:na]
at com.atlassian.security.auth.trustedapps.filter.TrustedApplicationsFilter.doFilter(TrustedApplicationsFilter.java:100) [TrustedApplicationsFilter.class:na]
at com.atlassian.oauth.serviceprovider.internal.servlet.OAuthFilter.doFilter(OAuthFilter.java:79) [atlassian-oauth-service-provider-plugin-1.9.9_1415929402000.jar:na]
at com.atlassian.analytics.client.filter.DefaultAnalyticsFilter.doFilter(DefaultAnalyticsFilter.java:32) [analytics-client-3.53_1414710896000.jar:na]
at com.atlassian.analytics.client.filter.AbstractHttpFilter.doFilter(AbstractHttpFilter.java:32) [analytics-client-3.53_1414710896000.jar:na]
at com.atlassian.stash.internal.web.auth.BeforeLoginPluginAuthenticationFilter.doBeforeBeforeLoginFilters(BeforeLoginPluginAuthenticationFilter.java:89) [BeforeLoginPluginAuthenticationFilter.class:na]
at com.atlassian.stash.internal.web.auth.BeforeLoginPluginAuthenticationFilter.doFilter(BeforeLoginPluginAuthenticationFilter.java:75) [BeforeLoginPluginAuthenticationFilter.class:na]
at com.atlassian.stash.internal.request.DefaultRequestManager.doAsRequest(DefaultRequestManager.java:85) [DefaultRequestManager.class:na]
at com.atlassian.stash.internal.hazelcast.ConfigurableWebFilter.doFilter(ConfigurableWebFilter.java:38) [ConfigurableWebFilter.class:na]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) [na:1.7.0_72]
at java.lang.Thread.run(Thread.java:745) [na:1.7.0_72]
... 254 frames trimmed