Either with Env-inject or SCM itself, the P4PASSWD will have additional single quote to it. see below:
....
OPTERR=1
OPTIND=1
OSTYPE=darwin13
P4CLIENT=client_mac--672026695
P4PASSWD='xxxxxx'
P4PORT=ssl:perforceserver:0000
P4USER=p4user
PATH='/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin'
....

then the error message:
Using remote perforce client: p4client_mac--672026695
[mac_node] $ /usr/bin/p4 workspace o p4client_mac-672026695
[mac_node] $ /usr/bin/p4 -p ssl:p4server:0000 trust -y
[mac_node] $ /usr/bin/p4 login -a -p
[mac_node] $ /usr/bin/p4 login -a -p
Caught exception communicating with perforce. Login attempt failed: Password invalid.com.tek42.perforce.PerforceException: Login attempt failed: Password invalid.
at com.tek42.perforce.parse.AbstractPerforceTemplate.p4Login(AbstractPerforceTemplate.java:639)
at com.tek42.perforce.parse.AbstractPerforceTemplate.login(AbstractPerforceTemplate.java:580)
at com.tek42.perforce.parse.AbstractPerforceTemplate.getPerforceResponse(AbstractPerforceTemplate.java:396)
at com.tek42.perforce.parse.AbstractPerforceTemplate.getPerforceResponse(AbstractPerforceTemplate.java:301)
at com.tek42.perforce.parse.Workspaces.getWorkspace(Workspaces.java:61)
at hudson.plugins.perforce.PerforceSCM.getPerforceWorkspace(PerforceSCM.java:1615)
at hudson.plugins.perforce.PerforceSCM.getPerforceWorkspace(PerforceSCM.java:1576)
at hudson.plugins.perforce.PerforceSCM.checkout(PerforceSCM.java:892)
at hudson.model.AbstractProject.checkout(AbstractProject.java:1252)
at hudson.model.AbstractBuild$AbstractBuildExecution.defaultCheckout(AbstractBuild.java:615)
at jenkins.scm.SCMCheckoutStrategy.checkout(SCMCheckoutStrategy.java:86)
at hudson.model.AbstractBuild$AbstractBuildExecution.run(AbstractBuild.java:524)
at hudson.model.Run.execute(Run.java:1710)
at hudson.model.FreeStyleBuild.run(FreeStyleBuild.java:43)
at hudson.model.ResourceController.execute(ResourceController.java:88)
at hudson.model.Executor.run(Executor.java:234)
ERROR: Unable to communicate with perforce. Login attempt failed: Password invalid.

please help!