Fix inputs trimming for variables

[aleksandrlevochkin]

WI

AB#2195400

Problem

Currently inputs are trimmed only before variables expansion, which does not account for the case when a variable with, for example, a leading space is defined, and then is passed as a task input:

variables:
  fileshare-path: ' \\fileshare\path'

steps:
- task: PublishBuildArtifacts@1
  inputs:
    PathtoPublish: '$(Build.ArtifactStagingDirectory)'
    ArtifactName: 'drop'
    publishLocation: 'FilePath '
    TargetPath: $(fileshare-path)

In the example above the target path input value will not be trimmed by the agent regardless of the DISABLE_INPUT_TRIMMING knob value.

Solution

Added trimming for variables after the expansion. This new behavior is disabled by default and can be enabled by setting the AGENT_ENABLE_VARIABLE_INPUT_TRIMMING knob to true.