Jenkins Perforce plugin can not parse where map on windows slave. It is not problem to do it on any other slave (running customized ubuntu), so problem is likely not on server. Tried multiple versions of P4 client (currently 2016.1).

$ p4 -G where //...
Caught exception communicating with perforce. Could not parse Where map.com.tek42.perforce.PerforceException: Could not parse Where map.
at hudson.plugins.perforce.PerforceSCMHelper.parseWhereMapping(PerforceSCMHelper.java:174)
at com.tek42.perforce.parse.Changes.calculateWorkspacePaths(Changes.java:83)
at com.tek42.perforce.parse.Changes.getChangelist(Changes.java:72)
at com.tek42.perforce.parse.Changes.getChangelistsFromNumbers(Changes.java:431)
at hudson.plugins.perforce.PerforceSCM.checkout(PerforceSCM.java:1073)
at hudson.model.AbstractProject.checkout(AbstractProject.java:1269)
at hudson.model.AbstractBuild$AbstractBuildExecution.defaultCheckout(AbstractBuild.java:607)
at jenkins.scm.SCMCheckoutStrategy.checkout(SCMCheckoutStrategy.java:86)
at hudson.model.AbstractBuild$AbstractBuildExecution.run(AbstractBuild.java:529)
at hudson.model.Run.execute(Run.java:1738)
at hudson.matrix.MatrixBuild.run(MatrixBuild.java:301)
at hudson.model.ResourceController.execute(ResourceController.java:98)
at hudson.model.Executor.run(Executor.java:410)
Caused by: java.io.IOException: Expected 's', but got '108'.
at hudson.plugins.perforce.PerforceSCMHelper.readPythonDictionary(PerforceSCMHelper.java:113)
at hudson.plugins.perforce.PerforceSCMHelper.parseWhereMapping(PerforceSCMHelper.java:149)
... 12 more
ERROR: Unable to communicate with perforce. Could not parse Where map.