AzureDevops pipeline task with condition not evaluated correctly

I have a pipeline which checks whether a commit has a tag and if that tag is a Version tag (meaning it is like 'v1.0.0' or 'v01.00.00').

My problem is that when I save the result of the regex operation in a variable, it appears to first be True but when using it in the condition of the second task it is suddenly False.

Here is the pipeline:

# Starter pipeline
# Start with a minimal pipeline that you can customize to build and deploy your code.
# Add steps that build, run tests, deploy, and more:
# https://aka.ms/yaml

trigger:
  branches:
    include:
      - master
  tags:
    include:
      - "*"

pool:
  vmImage: windows-latest

variables:
  hasTags: $[contains(variables['Build.SourceBranch'], 'refs/tags/')]
  isVersionTag: 'False'
  versionTag: ''

steps:

- task: PowerShell@2
  condition: eq(variables.hasTags, 'True')
  inputs:
    targetType: 'inline'
    script: |
      # get the tag the from the SourcheBranch
      $dummy = $Env:Build_SourceBranch
      $regex = "(refs)\/(tags)\/(?<version_tag>.+)$"
      $result = [regex]::Matches($dummy, $regex)
      $Env:versionTag = $result[0].Groups["version_tag"].Value

      # check if the tag is actually a version (e.g. 'v1.0.1')
      $regex = "v[0-9]{1,}\.[0-9]{1,}\.[0-9]{1,}$"
      $Env:isVersionTag = [regex]::IsMatch($Env:versionTag, $regex)

      if($Env:isVersionTag -eq 'True')
      {
        Write-Host 'It is a version tag'
      }

      Write-Host "Variable Build.SourceBranch = $Env:Build_SourceBranch"
      Write-Host "Variable isVersionTag = $Env:isVerionTag"
      Write-Host "Variable hasTags = $Env:hasTags"
      Write-Host "Variable versionTag = $Env:versionTag"      

# This will not run because the condition is evaluated as the following:
# Evaluating: and(eq(variables['hasTags'], 'True'), eq(variables['isVersionTag'], 'True'))
# Expanded: and(eq('True', 'True'), eq('False', 'True'))
# Result: False
- task: PowerShell@2
  condition: and(eq(variables.hasTags, 'True'), eq(variables.isVersionTag, 'True'))
  inputs:
    targetType: 'inline'
    script: |
      # Write your PowerShell commands here.
      
      Write-Host "The tag is a version tag"      

The output of the Write-Host of the above pipeline is the following:

It is a version tag
Variable Build.SourceBranch = refs/tags/v02.01.07
Variable isVersionTag = 
Variable hasTags = True
Variable versionTag = v02.01.07

The environment variables in PowerShell only contain strings, no booleans. In your case, they contain either the string "True" or the string "False". Either way, they contain something and the expression $Env:isVersionTag in the second example returns "False" which still is considered trueish. Use something like if($Env:isVersionTag -eq "True") instead, this should work.

To verify this behavior in any PowerShell window, you can do this:

$Env:testbool = $false
Write-Host $Env:testbool.GetType().FullName

I ended up replacing

$Env:isVersionTag = [regex]::IsMatch($Env:versionTag, $regex)

with

if([regex]::IsMatch($Env:versionTag, $regex))
{
   Write-Host "##vso[task.setvariable variable=isVersionTag]True"
}else{
   Write-Host "##vso[task.setvariable variable=isVersionTag]True"
}

and then it worked as expected.