Repository rule reading the file never reads it again, despite the file changed and rule re-run.

### Description of the problem / feature request:

If repository rule reads the file (with `repository_ctx.read`) subsequent rule executions don't try to read the file again, but assume previous values.

### Bugs: what's the simplest, easiest way to reproduce this bug? Please provide a minimal example if possible.

I have created compact repro [here](https://github.com/Bazel-snippets/read_file_repo_rule).
Command to run `bazel build do_nothing`
Test file `test_file.txt` does not exist and the rule correctly reports it.
Now create `test_file.txt` at the workspace root and run `bazel build do_nothing` - it still reports that the file does not exist!
This happens until Bazel is shutdown. The next run reports the file properly.

### What operating system are you running Bazel on?

Linux, Mac, Windows

### What's the output of `bazel info release`?

4.2.1