bib: mount devtmpfs inside the container too

This ensures that the new `partscan` feature in osbuild works. By
default the containers only have a static snapshot of /dev on a
tmpfs. This means that anything later added by losetup will be
missing inside the container.

It also means that https://github.com/osbuild/osbuild/pull/1468
can be reverted.

bib/internal/setup/setup.go

@@ -53,6 +53,14 @@ func EnsureEnvironment() error {
 	if err := util.RunCmdSync("mount", "--bind", destPath, osbuildPath); err != nil {
 		return err
 	}
+
+	// Ensure we have devfs inside the container to get dynamic loop
+	// loop devices inside the container.
+	devMnt := "/dev/"
+	if err := util.RunCmdSync("mount", "-t", "devtmpfs", "devtmpfs", devMnt); err != nil {
+		return err
+	}
+
 	return nil
 }