Top of negative bar renders over zero line

[winterlimelight]

Expected Behavior

A bar is expected to have the zero-line as one of the borders

Current Behavior

Bars with negative values start from the zero-line, rather than below it, meaning they lack the top border.

Steps to Reproduce (for bugs)

https://jsfiddle.net/winter_limelight/zxd0b81c/9/

Note that the red line is absent from the Mar 18 bar.

var ctx = document.getElementById("chart").getContext('2d');
var chart = new Chart(ctx, {
  type: 'bar',
  data: {
    labels: ['Feb 18', 'Mar 18'],
    datasets: [{
      backgroundColor: '#AAFFCC',
      borderColor: '#0000FF',
      borderWidth: 1,
      data: [1, -1]
    }]
  },
  options: {
    scales: {
      yAxes: [{
        gridLines: {
          zeroLineColor: '#FF0000'
        },
      }]
    },
    maintainAspectRatio: false
  }
});

Setting maintainAspectRatio: true changes the border behaviour, but doesn't fix the issue.

Context

Presently trying to create chart showing historical +ve/-ve percentage changes for a client.

Environment

Chart.js version: 2.7.3
Browser name and version: Noted in Chrome 71, Firefox 64.

[kurkle]

This is a bit different in master: https://jsfiddle.net/wkec8d9u/ (still a bug though IMO)

[etimberg]

Tested master and now the red line is missing on the positive bar https://jsfiddle.net/pqfdrvz3/

[kurkle]

dpr: 1

dpr: 1.25

dpr: 2.5