I think the -rev parameter should be used only if a rev is specified.

In my case hg clone http://bbmustdqa/hg/Outlook%20ES is a valid command but

hg clone --rev default http://bbmustdqa/hg/Outlook%20ES is not. Not sure if the IOException is a side effect or another issue.

Here's my output:

Started by user ortijaus
$ hg clone --rev default http://bbmustdqa/hg/Outlook%20ES "C:\.hudson\jobs\Outlook ES MP\workspace"
abort: unknown revision 'default'!
ERROR: Failed to clone http://bbmustdqa/hg/Outlook%20ES
[workspace] $ hg log --rev . --template

java.io.IOException: Cannot run program "hg" (in directory "C:\.hudson\jobs\Outlook ES MP\workspace"): CreateProcess error=267, The directory name is invalid
at java.lang.ProcessBuilder.start(Unknown Source)
at hudson.Proc$LocalProc.<init>(Proc.java:192)
at hudson.Proc$LocalProc.<init>(Proc.java:164)
at hudson.Launcher$LocalLauncher.launch(Launcher.java:638)
at hudson.Launcher$ProcStarter.start(Launcher.java:273)
at hudson.Launcher$ProcStarter.join(Launcher.java:280)
at hudson.plugins.mercurial.MercurialSCM.joinWithPossibleTimeout(MercurialSCM.java:297)
at hudson.plugins.mercurial.HgExe.popen(HgExe.java:190)
at hudson.plugins.mercurial.HgExe.tip(HgExe.java:170)
at hudson.plugins.mercurial.MercurialSCM.calcRevisionsFromBuild(MercurialSCM.java:254)
at hudson.scm.SCM._calcRevisionsFromBuild(SCM.java:304)
at hudson.model.AbstractProject.calcPollingBaseline(AbstractProject.java:1131)
at hudson.model.AbstractProject.checkout(AbstractProject.java:1120)
at hudson.model.AbstractBuild$AbstractRunner.checkout(AbstractBuild.java:480)
at hudson.model.AbstractBuild$AbstractRunner.run(AbstractBuild.java:412)
at hudson.model.Run.run(Run.java:1325)
at hudson.model.FreeStyleBuild.run(FreeStyleBuild.java:46)
at hudson.model.ResourceController.execute(ResourceController.java:88)
at hudson.model.Executor.run(Executor.java:139)
Caused by: java.io.IOException: CreateProcess error=267, The directory name is invalid
at java.lang.ProcessImpl.create(Native Method)
at java.lang.ProcessImpl.<init>(Unknown Source)
at java.lang.ProcessImpl.start(Unknown Source)
... 19 more