fixups to avoid single tick

Author: archmoj

src/plots/cartesian/axes.js

@@ -624,7 +624,7 @@ axes.calcTicks = function calcTicks(ax) {
         // replace ticks inside breaks that would get a tick
         // and reduce ticks
         var len = tickVals.length;
-        if(len > 2) {
+        if(len) {
             var tf = 0;
             if(ax.tickmode === 'auto') {
                 tf =

test/image/baselines/axes_breaks-contour1d.png

@@ -856,6 +856,7 @@
             "text": "1D-z-array contour with rangebreaks"
         },
         "xaxis": {
+            "dtick": 1800000,
             "rangebreaks": [
                 {
                     "pattern": "hour",

test/image/baselines/axes_breaks-contour2d.png

@@ -128,6 +128,7 @@
             "text": "2D-z-array contour with rangebreaks"
         },
         "xaxis": {
+            "dtick": 1800000,
             "rangebreaks": [
                 {
                     "pattern": "hour",

test/image/baselines/axes_breaks-heatmap1d.png

@@ -856,6 +856,7 @@
             "text": "1D-z-array heatmap with rangebreaks"
         },
         "xaxis": {
+            "dtick": 1800000,
             "rangebreaks": [
                 {
                     "pattern": "hour",

test/image/baselines/axes_breaks-heatmap2d.png

@@ -128,6 +128,7 @@
             "text": "2D-z-array heatmap with rangebreaks"
         },
         "xaxis": {
+            "dtick": 1800000,
             "rangebreaks": [
                 {
                     "pattern": "hour",

test/image/baselines/axes_breaks-histogram2d.png

@@ -482,6 +482,7 @@
         "2020-01-02 16:55",
         "2020-01-03 09:55"
       ],
+      "dtick": 1800000,
       "rangebreaks": [{
         "pattern": "hour",
         "bounds": [18, 9]