Fix hover label exponent hiding or gl3d log hover

src/plots/cartesian/axes.js

@@ -1298,6 +1298,17 @@ function formatDate(ax, out, hover, extraPrecision) {
 function formatLog(ax, out, hover, extraPrecision, hideexp) {
     var dtick = ax.dtick,
         x = out.x;
+
+    if(hideexp === 'never') {
+        // If this is a hover label, then we must *never* hide the exponent
+        // for the sake of display, which could give the wrong value by
+        // potentially many orders of magnitude. If hideexp was 'never', then
+        // it's now succeeded by preventing the other condition from automating
+        // this choice. Thus we can unset it so that the axis formatting takes
+        // precedence.
+        hideexp = '';
+    }
+
     if(extraPrecision && ((typeof dtick !== 'string') || dtick.charAt(0) !== 'L')) dtick = 'L3';
 
     if(ax.tickformat || (typeof dtick === 'string' && dtick.charAt(0) === 'L')) {

test/jasmine/tests/hover_label_test.js

@@ -199,6 +199,26 @@ describe('hover info', function() {
         });
     });
 
+    describe('hover info y on log axis', function() {
+        var mockCopy = Lib.extendDeep({}, mock);
+
+        mockCopy.data[0].hoverinfo = 'y';
+
+        beforeEach(function(done) {
+            for(var i = 0; i < mockCopy.data[0].y.length; i++) {
+                mockCopy.data[0].y[i] *= 1e9;
+            }
+
+            Plotly.plot(createGraphDiv(), mockCopy.data, mockCopy.layout).then(done);
+        });
+
+        it('responds to hover y+text', function() {
+            Fx.hover('graph', evt, 'xy');
+
+            expect(d3.selectAll('g.hovertext').selectAll('text.nums').node().innerHTML).toEqual('1e+9');
+        });
+    });
+
     describe('hover info y+text', function() {
         var mockCopy = Lib.extendDeep({}, mock);