Global vars evaluation doesn't work when calling task from another task.

[Thomy90]

Hi guys,
I found another bug.

After calling call-default task in example below.

version: '3'

vars:
  FOO: '{{ default "foo" .FOO}}'
  BAZ: '{{.FOO}}'

tasks:
  default:
    cmds:
      - echo {{.BAZ}}

  call-default:
    cmds:
      - task: default
        vars:
          FOO: 'new-foo'

Expected output:

task: [default] echo foo
new-foo

Actual output:

task: [default] echo foo
foo

• Task version: 3.28.0
• Operating system: Ubuntu 20.04.6
• Experiments enabled: no