Fix go:embed failing to add embedsrcs for subdirectories named bu…

…ild (bazel-contrib#1539)

* Only consider filepath with build in the name only if they are not directories

* Add tests for the nested build directory

language/go/embed.go

@@ -130,7 +130,7 @@ func newEmbedResolver(dir, rel string, validBuildFileNames []string, pkgRels map
 				return filepath.SkipDir
 			}
 			for _, name := range validBuildFileNames {
-				if _, err := os.Stat(filepath.Join(p, name)); err == nil {
+				if bFileInfo, err := os.Stat(filepath.Join(p, name)); err == nil && !bFileInfo.IsDir() {
 					// Directory already contains a build file.
 					return filepath.SkipDir
 				}

language/go/testdata/embedsrcs/BUILD.want

@@ -11,6 +11,7 @@ go_library(
         "m_static.txt",
         "n_/static.txt",
         "o_dir/_hidden.txt",
+        "p_dir/build.old/static.txt",
     ],
     importpath = "example.com/repo/embedsrcs",
     visibility = ["//visibility:public"],

language/go/testdata/embedsrcs/embedsrcs.go

@@ -2,5 +2,5 @@ package embedsrcs
 
 import "embed"
 
-//go:embed *m_* n_/* all:o*
+//go:embed *m_* n_/* p_dir/* all:o*
 var fs embed.FS

language/go/testdata/embedsrcs/p_dir/build.old/static.txt

@@ -0,0 +1,2 @@
+# p_dir/build.old/static.txt should be embedded because while the subdirectory is named `build.old`,
+# it is a directory and not an actual BUILD file.