Schedule ordinary import contributions by dependency

internal/engine/source_context.go

@@ -23,9 +23,16 @@ func contextsForAcquiredSources(source Source, context *FilesystemContext, baseS
 		filesystem = context.FS.namespace.filesystem
 		rootPath, basePath = context.Root, context.BaseDir
 	} else if source.kind == sourceFile {
-		filePath := sources[0].Path
+		filePath := source.path
 		if baseSource != nil {
 			filePath = baseSource.Path
+		} else {
+			canonical, err := canonicalExistingPath(filePath)
+			if err != nil {
+				value := importDiagnostic(CodeImportInvalid, "selected source could not be canonicalized", nil)
+				return nil, &value
+			}
+			filePath = canonical
 		}
 		basePath = filepath.Dir(filePath)
 		rootPath = basePath