cmd/go: fix vendoredImportPath comment

Change-Id: I1650124dd459dc401ccd73943ff7287b1b8c57e4
Reviewed-on: https://go-review.googlesource.com/13689Reviewed-by: Andrew Gerrand <adg@golang.org>

src/cmd/go/pkg.go

@@ -406,7 +406,7 @@ func isDir(path string) bool {
 
 // vendoredImportPath returns the expansion of path when it appears in parent.
 // If parent is x/y/z, then path might expand to x/y/z/vendor/path, x/y/vendor/path,
-// x/vendor/path, vendor/path, or else stay x/y/z if none of those exist.
+// x/vendor/path, vendor/path, or else stay path if none of those exist.
 // vendoredImportPath returns the expanded path or, if no expansion is found, the original.
 // If no expansion is found, vendoredImportPath also returns a list of vendor directories
 // it searched along the way, to help prepare a useful error message should path turn