configSubmit triggers a JSON Error in folowing configuration:
_ have a slave jenkins attached
_ have a free project config with more than one build step (e.g. 2 windows batch)

[works fine for each condition but not when the 2 are encountered]

Error message : (XXX replaced internal strings)
Error

Failed to parse form data. Please report this problem as a bug
JSON={"":"XXX","blockBuildWhenUpstreamBuilding":{},"builder":"\"[

{\"command\":\"XXX\",\"stapler-class\":\"hudson.tasks.BatchFile\",\"kind\":\"hudson.tasks.BatchFile\"}

,

{\"command\":\"XXX\",\"stapler-class\":\"hudson.tasks.BatchFile\",\"kind\":\"hudson.tasks.BatchFile\"}

]\"","description":"XXX","hasSlaveAffinity":

{"assignedLabelString":"master"}

,"hudson-tasks-BuildTrigger":

{"childProjects":"XXX","threshold":"SUCCESS"}

,"hudson-tasks-Mailer":

{"mailer_notifyEveryUnstableBuild":false,"mailer_recipients":"XXX","mailer_sendToIndividuals":false}

,"hudson-triggers-TimerTrigger":

{"spec":"0 2 * * 0"}

,"logrotate":

{"logrotate_artifact_days":"","logrotate_artifact_nums":"","logrotate_days":"","logrotate_nums":"1"}

,"name":"XXX","properties":{"hudson-model-ParametersDefinitionProperty":{},"hudson-plugins-heavy_job-HeavyJobProperty":

{"weight":"4"}

,"hudson-security-AuthorizationMatrixProperty":{},"stapler-class-bag":"true"},"scm":{"value":"1"}}

net.sf.json.JSONException: A JSONArray text must start with '[' at character 1 of "[

{"command":"XXX","stapler-class":"hudson.tasks.BatchFile","kind":"hudson.tasks.BatchFile"}

,

{"command":"XXX","stapler-class":"hudson.tasks.BatchFile","kind":"hudson.tasks.BatchFile"}

]"
at net.sf.json.util.JSONTokener.syntaxError(JSONTokener.java:512)
at net.sf.json.JSONArray._fromJSONTokener(JSONArray.java:903)
at net.sf.json.JSONArray._fromString(JSONArray.java:983)
at net.sf.json.JSONArray.fromObject(JSONArray.java:141)
at net.sf.json.JSONArray.fromObject(JSONArray.java:120)
at hudson.model.Descriptor.newInstancesFromHeteroList(Descriptor.java:863)
at hudson.model.Descriptor.newInstancesFromHeteroList(Descriptor.java:853)
at hudson.util.DescribableList.rebuildHetero(DescribableList.java:185)
at hudson.model.Project.submit(Project.java:197)
at hudson.model.Job.doConfigSubmit(Job.java:966)
at hudson.model.AbstractProject.doConfigSubmit(AbstractProject.java:643)
at sun.reflect.GeneratedMethodAccessor450.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at org.kohsuke.stapler.Function$InstanceFunction.invoke(Function.java:282)
at org.kohsuke.stapler.Function.bindAndInvoke(Function.java:149)
at org.kohsuke.stapler.Function.bindAndInvokeAndServeResponse(Function.java:88)
at org.kohsuke.stapler.MetaClass$1.doDispatch(MetaClass.java:104)
at org.kohsuke.stapler.NameBasedDispatcher.dispatch(NameBasedDispatcher.java:53)
at org.kohsuke.stapler.Stapler.tryInvoke(Stapler.java:561)
at org.kohsuke.stapler.Stapler.invoke(Stapler.java:646)
at org.kohsuke.stapler.MetaClass$6.doDispatch(MetaClass.java:234)
at org.kohsuke.stapler.NameBasedDispatcher.dispatch(NameBasedDispatcher.java:53)
at org.kohsuke.stapler.Stapler.tryInvoke(Stapler.java:561)
at org.kohsuke.stapler.Stapler.invoke(Stapler.java:646)
at org.kohsuke.stapler.MetaClass$6.doDispatch(MetaClass.java:234)
at org.kohsuke.stapler.NameBasedDispatcher.dispatch(NameBasedDispatcher.java:53)
at org.kohsuke.stapler.Stapler.tryInvoke(Stapler.java:561)
at org.kohsuke.stapler.Stapler.invoke(Stapler.java:646)
at org.kohsuke.stapler.Stapler.invoke(Stapler.java:477)
at org.kohsuke.stapler.Stapler.service(Stapler.java:159)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:45)
at winstone.ServletConfiguration.execute(ServletConfiguration.java:249)
at winstone.RequestDispatcher.forward(RequestDispatcher.java:335)
at winstone.RequestDispatcher.doFilter(RequestDispatcher.java:378)
at hudson.util.PluginServletFilter$1.doFilter(PluginServletFilter.java:95)
at hudson.util.PluginServletFilter.doFilter(PluginServletFilter.java:87)
at winstone.FilterConfiguration.execute(FilterConfiguration.java:195)
at winstone.RequestDispatcher.doFilter(RequestDispatcher.java:368)
at hudson.security.csrf.CrumbFilter.doFilter(CrumbFilter.java:47)
at winstone.FilterConfiguration.execute(FilterConfiguration.java:195)
at winstone.RequestDispatcher.doFilter(RequestDispatcher.java:368)
at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:84)
at hudson.security.UnwrapSecurityExceptionFilter.doFilter(UnwrapSecurityExceptionFilter.java:51)
at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87)
at org.acegisecurity.ui.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:166)
at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87)
at org.acegisecurity.providers.anonymous.AnonymousProcessingFilter.doFilter(AnonymousProcessingFilter.java:125)
at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87)
at org.acegisecurity.ui.rememberme.RememberMeProcessingFilter.doFilter(RememberMeProcessingFilter.java:142)
at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87)
at org.acegisecurity.ui.AbstractProcessingFilter.doFilter(AbstractProcessingFilter.java:271)
at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87)
at org.acegisecurity.ui.basicauth.BasicProcessingFilter.doFilter(BasicProcessingFilter.java:173)
at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87)
at jenkins.security.ApiTokenFilter.doFilter(ApiTokenFilter.java:61)
at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87)
at org.acegisecurity.context.HttpSessionContextIntegrationFilter.doFilter(HttpSessionContextIntegrationFilter.java:249)
at hudson.security.HttpSessionContextIntegrationFilter2.doFilter(HttpSessionContextIntegrationFilter2.java:66)
at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87)
at hudson.security.ChainedServletFilter.doFilter(ChainedServletFilter.java:76)
at hudson.security.HudsonFilter.doFilter(HudsonFilter.java:164)
at winstone.FilterConfiguration.execute(FilterConfiguration.java:195)
at winstone.RequestDispatcher.doFilter(RequestDispatcher.java:368)
at hudson.util.CharacterEncodingFilter.doFilter(CharacterEncodingFilter.java:81)
at winstone.FilterConfiguration.execute(FilterConfiguration.java:195)
at winstone.RequestDispatcher.doFilter(RequestDispatcher.java:368)
at winstone.RequestDispatcher.forward(RequestDispatcher.java:333)
at winstone.RequestHandlerThread.processRequest(RequestHandlerThread.java:244)
at winstone.RequestHandlerThread.run(RequestHandlerThread.java:150)
at java.lang.Thread.run(Unknown Source)