Fix race while running helm dep build on local chart

Resolves #1438

pkg/state/state.go

@@ -81,6 +81,9 @@ type HelmState struct {
 	runner      helmexec.Runner
 	valsRuntime vals.Evaluator
 
+	depBuiltChartsMu sync.Mutex
+	depBuiltCharts   map[string]bool
+
 	// If set to "Error", return an error when a subhelmfile points to a
 	// non-existent path. The default behavior is to print a warning. Note the
 	// differing default compared to other MissingFileHandlers.
@@ -924,7 +927,19 @@ func (st *HelmState) PrepareCharts(helm helmexec.Interface, dir string, concurre
 					// a broken remote chart won't completely block their job.
 					chartPath = normalizeChart(st.basePath, chartPath)
 
-					if !opts.SkipRepos {
+					var doBuildDeps bool
+
+					(&st.depBuiltChartsMu).Lock()
+					if st.depBuiltCharts == nil {
+						st.depBuiltCharts = map[string]bool{}
+					}
+					if !st.depBuiltCharts[chartPath] {
+						st.depBuiltCharts[chartPath] = true
+						doBuildDeps = true
+					}
+					(&st.depBuiltChartsMu).Unlock()
+
+					if !opts.SkipRepos && doBuildDeps {
 						if err := helm.BuildDeps(release.Name, chartPath); err != nil {
 							if chartFetchedByGoGetter {
 								diagnostic = fmt.Sprintf(