name too long open base64 image

# Expected Behavior
jimp can read image url

# Current Behavior
jimp can't read image url

# Failure Information (for bugs)
name too long open 'data:image/jpeg;base64,...'

## Steps to Reproduce

```
Jimg.read(this.orignSrc).then(image => {
image.color([{apply: val, params: [100]}]).getBase64(Jimg.AUTO, (err, src) => {
this.doingImg.src = src;
});
});
```
then I got 'name too long, open "data:image/jpeg;base64,..."'
this.orignSrc is a base64 image

**Screenshots**


## Context

sorry, none
- Jimp Version: 0.6.4
- Operating System: macOS 10.13.6
- Node version: v10.15.0

## Failure Logs