Clarify debug and error messages regarding piece verification

Specify whether the verification was on a piece in the store, or on a piece from a wire.

lib/torrent.js

@@ -630,7 +630,7 @@ Torrent.prototype._verify = function (index, cb) {
       if (self.bitfield.get(index)) return cb(null)
 
       if (hash === self._hashes[index]) {
-        self._debug('piece verified %s', index)
+        self._debug('piece from store verified %s', index)
         self._markInStore(index)
 
         self.wires.forEach(function (wire) {
@@ -645,7 +645,7 @@ Torrent.prototype._verify = function (index, cb) {
 
         cb(null)
       } else {
-        self._debug('piece invalid %s', index)
+        self._debug('piece from store invalid %s', index)
         self._verified[index] = true
         self._update()
         cb(null)
@@ -1568,7 +1568,7 @@ Torrent.prototype._request = function (wire, index, hotswap) {
 
       if (hash === self._hashes[index]) {
         if (!self.pieces[index]) return
-        self._debug('piece verified %s', index)
+        self._debug('piece from wire verified %s', index)
 
         self.pieces[index] = null
         self._reservations[index] = null
@@ -1585,7 +1585,7 @@ Torrent.prototype._request = function (wire, index, hotswap) {
         if (self._checkDone() && !self.destroyed) self.discovery.complete()
       } else {
         self.pieces[index] = new Piece(piece.length)
-        self.emit('warning', new Error('Piece ' + index + ' failed verification'))
+        self.emit('warning', new Error('Piece from wire ' + index + ' failed verification'))
       }
       onUpdateTick()
     })