Modifying a global library stored in Perforce when replaying a job fails due file not being writable. 

Looks like when you replay a job in Jenkins and make a change to the library file, Jenkins then attempts to write to the file. Due to the file not being open for edit when Jenkins attempts to write to the file this subsequently fails.

https://github.com/jenkinsci/p4-plugin/pull/85

Reproduction steps:

• create a folder
• add a library within the folder
• create a pipeline job(inline script or jenkinsfile) within the folder
• build the job at least once
• select the replay option for one of your finished jobs
• on the "replay job" screen modify the library file before you replay
• replay the job by selecting the "run" button