File does not validate as base64

[This](
http://www.oxerfarm.com/images/smalltest.pdf) PDF-file does not validate as a valid base64. Any idea why?

```js
const fs = require('fs')
const base64Regex = require('base64-regex')
const b64 = fs.readFileSync('./smalltest.pdf' ,'base64')
console.log(b64) // missing == at end
console.log(base64Regex().test(b64)) // false
```

Reproduce the report using the provided Node.js snippet and the linked PDF input. Then inspect the package's base64 validation entry point to compare its behavior with the string produced by fs.readFileSync; done means establishing whether the validator or the reported expectation is incorrect.

Written by the indexing model from the issue text.