chore: prevent 'false positive' data race detection with Job.If [skip cascade] (#864)

Initialization of the default value of the `If` field is functionally safe, but triggers the data race detector.

```
==================
WARNING: DATA RACE
Read at 0x00c00037cf78 by goroutine 10:
  code.forgejo.org/forgejo/runner/v9/act/model.(*Workflow).GetJob()
      /.../forgejo-runner/act/model/workflow.go:766 +0x2ae
  code.forgejo.org/forgejo/runner/v9/act/model.(*Run).Job()
      /.../forgejo-runner/act/model/planner.go:50 +0xab
  code.forgejo.org/forgejo/runner/v9/act/runner.setJobResult()
      /.../forgejo-runner/act/runner/job_executor.go:168
+0x7c
  code.forgejo.org/forgejo/runner/v9/act/runner.TestSetJobResultConcurrency.func3()
      /.../forgejo-runner/act/runner/job_executor_test.go:410
+0xf8

Previous write at 0x00c00037cf78 by goroutine 9:
  code.forgejo.org/forgejo/runner/v9/act/model.(*Workflow).GetJob()
      /.../forgejo-runner/act/model/workflow.go:767 +0x2ce
  code.forgejo.org/forgejo/runner/v9/act/model.(*Run).Job()
      /.../forgejo-runner/act/model/planner.go:50 +0xab
  code.forgejo.org/forgejo/runner/v9/act/runner.setJobResult()
      /.../forgejo-runner/act/runner/job_executor.go:168
+0x7c
  code.forgejo.org/forgejo/runner/v9/act/runner.TestSetJobResultConcurrency.func2()
      /.../forgejo-runner/act/runner/job_executor_test.go:405
+0xfb

Goroutine 10 (running) created at:
  code.forgejo.org/forgejo/runner/v9/act/runner.TestSetJobResultConcurrency()
      /.../forgejo-runner/act/runner/job_executor_test.go:408
+0xbac
  testing.tRunner()
      /home/mfenniak/go/pkg/mod/golang.org/toolchain@v0.0.1-go1.24.6.linux-amd64/src/testing/testing.go:1792
+0x225
  testing.(*T).Run.gowrap1()
      /home/mfenniak/go/pkg/mod/golang.org/toolchain@v0.0.1-go1.24.6.linux-amd64/src/testing/testing.go:1851
+0x44

Goroutine 9 (running) created at:
  code.forgejo.org/forgejo/runner/v9/act/runner.TestSetJobResultConcurrency()
      /.../forgejo-runner/act/runner/job_executor_test.go:403
+0xa84
  testing.tRunner()
      /home/mfenniak/go/pkg/mod/golang.org/toolchain@v0.0.1-go1.24.6.linux-amd64/src/testing/testing.go:1792
+0x225
  testing.(*T).Run.gowrap1()
      /home/mfenniak/go/pkg/mod/golang.org/toolchain@v0.0.1-go1.24.6.linux-amd64/src/testing/testing.go:1851
+0x44
==================
```

<!--start release-notes-assistant-->
<!--URL:https://code.forgejo.org/forgejo/runner-->
- other
  - [PR](https://code.forgejo.org/forgejo/runner/pulls/864): <!--number 864 --><!--line 0 --><!--description Y2hvcmU6IHByZXZlbnQgJ2ZhbHNlIHBvc2l0aXZlJyBkYXRhIHJhY2UgZGV0ZWN0aW9uIHdpdGggSm9iLklmIFtza2lwIGNhc2NhZGVd-->chore: prevent 'false positive' data race detection with Job.If [skip cascade]<!--description-->
<!--end release-notes-assistant-->

Reviewed-on: https://code.forgejo.org/forgejo/runner/pulls/864
Reviewed-by: earl-warren <earl-warren@noreply.code.forgejo.org>
Co-authored-by: Mathieu Fenniak <mathieu@fenniak.net>
Co-committed-by: Mathieu Fenniak <mathieu@fenniak.net>

act/model/workflow.go

@@ -207,7 +207,7 @@ type Job struct {
 	RawNeeds       yaml.Node                 `yaml:"needs"`
 	RawRunsOn      yaml.Node                 `yaml:"runs-on"`
 	Env            yaml.Node                 `yaml:"env"`
-	If             yaml.Node                 `yaml:"if"`
+	RawIf          yaml.Node                 `yaml:"if"`
 	Steps          []*Step                   `yaml:"steps"`
 	TimeoutMinutes string                    `yaml:"timeout-minutes"`
 	Services       map[string]*ContainerSpec `yaml:"services"`
@@ -362,6 +362,13 @@ func (j *Job) RunsOn() []string {
 	}
 }
 
+func (j *Job) IfClause() string {
+	if j.RawIf.Value == "" {
+		return "success()"
+	}
+	return j.RawIf.Value
+}
+
 func nodeAsStringSlice(node yaml.Node) []string {
 	switch node.Kind {
 	case yaml.ScalarNode:
@@ -761,9 +768,6 @@ func (w *Workflow) GetJob(jobID string) *Job {
 			if j.Name == "" {
 				j.Name = id
 			}
-			if j.If.Value == "" {
-				j.If.Value = "success()"
-			}
 			return j
 		}
 	}

act/runner/run_context.go

@@ -1022,11 +1022,11 @@ func (rc *RunContext) options(ctx context.Context) string {
 func (rc *RunContext) isEnabled(ctx context.Context) (bool, error) {
 	job := rc.Run.Job()
 	l := common.Logger(ctx)
-	runJob, runJobErr := EvalBool(ctx, rc.ExprEval, job.If.Value, exprparser.DefaultStatusCheckSuccess)
+	runJob, runJobErr := EvalBool(ctx, rc.ExprEval, job.IfClause(), exprparser.DefaultStatusCheckSuccess)
 	jobType, jobTypeErr := job.Type()
 
 	if runJobErr != nil {
-		return false, fmt.Errorf("  \u274C  Error in if-expression: \"if: %s\" (%s)", job.If.Value, runJobErr)
+		return false, fmt.Errorf("  \u274C  Error in if-expression: \"if: %s\" (%s)", job.IfClause(), runJobErr)
 	}
 
 	if jobType == model.JobTypeInvalid {
@@ -1035,7 +1035,7 @@ func (rc *RunContext) isEnabled(ctx context.Context) (bool, error) {
 
 	if !runJob {
 		rc.result("skipped")
-		l.WithField("jobResult", "skipped").Infof("Skipping job '%s' due to '%s'", job.Name, job.If.Value)
+		l.WithField("jobResult", "skipped").Infof("Skipping job '%s' due to '%s'", job.Name, job.IfClause())
 		return false, nil
 	}
 

act/runner/runner.go

@@ -154,7 +154,7 @@ func (runner *runnerImpl) NewPlanExecutor(plan *model.Plan) common.Executor {
 				log.Debugf("Job.RawNeeds: %v", job.RawNeeds)
 				log.Debugf("Job.RawRunsOn: %v", job.RawRunsOn)
 				log.Debugf("Job.Env: %v", job.Env)
-				log.Debugf("Job.If: %v", job.If)
+				log.Debugf("Job.If: %v", job.IfClause())
 				for step := range job.Steps {
 					if nil != job.Steps[step] {
 						log.Debugf("Job.Steps: %v", job.Steps[step].String())