Error logged when schedule poll changes in the SCM and using variables in Stream Codeline field

Steps:

1. Create a Free Style Project
2. Choose 'This project is parameterized'.
3. Create a 'String' parameter with name 'STREAM' and a default value of a known stream (e.g. '//streams/main/project/version').
4. Under 'Source Code Management' choose 'Perforce Software', enter the credentials
5. Under Workspace behavior 'Streams'.
6. Set 'Stream Codeline' to ${STREAM}'.
7. Under 'Build Triggers', enable Poll SCM, Set Schedule to poll every 5 minutes 'H/5 * * * *'
8. Save.
9. Choose 'Build with Parameters' to build once or wait the first polling triggered successfully
10. After 1st successful build, wait 5 minutes for the next polling, following is logged in the Perforce Software Polling Log.

P4: Unable to setup workspace: com.perforce.p4java.exception.RequestException: Error in client specification.
Error detected at line 18.
Stream 'STREAM' must begin with '//'.

	at com.perforce.p4java.impl.mapbased.server.cmd.ResultMapParser.handleErrorStr(ResultMapParser.java:151)
	at com.perforce.p4java.impl.mapbased.server.cmd.ResultMapParser.parseCommandResultMapIfIsInfoMessageAsString(ResultMapParser.java:102)
	at com.perforce.p4java.impl.mapbased.server.cmd.ClientDelegator.updateClient(ClientDelegator.java:212)
	at com.perforce.p4java.impl.mapbased.server.Server.updateClient(Server.java:1784)
	at com.perforce.p4java.impl.mapbased.client.Client.update(Client.java:524)
	at org.jenkinsci.plugins.p4.client.ClientHelper.updateClient(ClientHelper.java:191)
	at org.jenkinsci.plugins.p4.client.ClientHelper.clientLogin(ClientHelper.java:170)
	at org.jenkinsci.plugins.p4.client.ClientHelper.<init>(ClientHelper.java:104)
	at org.jenkinsci.plugins.p4.tasks.AbstractTask.tryTask(AbstractTask.java:171)
	at org.jenkinsci.plugins.p4.tasks.PollTask.invoke(PollTask.java:50)
	at org.jenkinsci.plugins.p4.tasks.PollTask.invoke(PollTask.java:33)
	at hudson.FilePath.act(FilePath.java:1200)
	at hudson.FilePath.act(FilePath.java:1183) 

Note: 

• Issue is similar to JENKINS-56775 but only poll SCM has this issue. Triggering build manually is successful and no such error logged.
• Tried to set stream variables without "//" characters and find the parameters is not replaced 
  • set variable STREAM1 = streams
  • set variable STREAM2 = main/project/version
  • set the Stream Codeline to //${STREAM1}/${STREAM2}
  • following error is logged in the polling log and seems the variable is not replaced

  • P4: Unable to setup workspace: com.perforce.p4java.exception.RequestException: Error in client specification.
    Stream '//STREAM1/STREAM2' doesn't exist.
    
    	at com.perforce.p4java.impl.mapbased.server.cmd.ResultMapParser.handleErrorStr(ResultMapParser.java:151)
    	at com.perforce.p4java.impl.mapbased.server.cmd.ResultMapParser.parseCommandResultMapIfIsInfoMessageAsString(ResultMapParser.java:102)
    	at com.perforce.p4java.impl.mapbased.server.cmd.ClientDelegator.updateClient(ClientDelegator.java:212)