Correcly handle folds that end where other folds begin

Fixes #2247

spec/display-buffer-spec.coffee

@@ -315,6 +315,16 @@ describe "DisplayBuffer", ->
           expect(line0.fold).toBe outerFold
           expect(line1.fold).toBeUndefined()
 
+      describe "when a fold ends where another fold begins", ->
+        it "continues to hide the lines inside the second fold", ->
+          fold2 = displayBuffer.createFold(4, 9)
+          fold1 = displayBuffer.createFold(0, 4)
+
+          displayBuffer.logLines(0, 20)
+
+          expect(displayBuffer.lineForRow(0).text).toMatch /^0/
+          expect(displayBuffer.lineForRow(1).text).toMatch /^10/
+
       describe "when there is another display buffer pointing to the same buffer", ->
         it "does not create folds in the other display buffer", ->
           otherDisplayBuffer = new DisplayBuffer({buffer, tabLength})

src/fold.coffee

@@ -35,6 +35,11 @@ class Fold
   # Returns a {Range}.
   getBufferRange: ({includeNewline}={}) ->
     range = @marker.getRange()
+
+    if range.end.row > range.start.row and nextFold = @displayBuffer.largestFoldStartingAtBufferRow(range.end.row)
+      nextRange = nextFold.getBufferRange()
+      range = new Range(range.start, nextRange.end)
+
     if includeNewline
       range = range.copy()
       range.end.row++