if a range has no end still collapse the start (#117)

Author: mafintosh

lib/replicator.js

@@ -1191,7 +1191,7 @@ module.exports = class Replicator {
       for (let i = 0; i < this._ranges.length; i++) {
         const r = this._ranges[i]
 
-        while (r.start < r.end && this.core.bitfield.get(mapIndex(r.blocks, r.start)) === true) r.start++
+        while ((r.end === -1 || r.start < r.end) && this.core.bitfield.get(mapIndex(r.blocks, r.start)) === true) r.start++
         while (r.start < r.end && this.core.bitfield.get(mapIndex(r.blocks, r.end - 1)) === true) r.end--
 
         if (r.end !== -1 && r.start >= r.end) {