Add indentBasis metadata to pasteboard when copying text

This allows indent to be normalized properly even if the leading whitespace isn't copied from the first line.

spec/app/edit-session-spec.coffee

@@ -1328,6 +1328,18 @@ describe "EditSession", ->
           expect(editSession.buffer.lineForRow(0)).toBe "var first = function () {"
           expect(buffer.lineForRow(1)).toBe "  var first = function(items) {"
 
+      it "preserves the indent level when copying and pasting multiple lines", ->
+        editSession.setAutoIndent(true)
+        editSession.setSelectedBufferRange([[4, 4], [7, 5]])
+        editSession.copySelectedText()
+        editSession.setCursorBufferPosition([10, 0])
+        editSession.pasteText()
+
+        expect(editSession.lineForBufferRow(10)).toBe "  while(items.length > 0) {"
+        expect(editSession.lineForBufferRow(11)).toBe "    current = items.shift();"
+        expect(editSession.lineForBufferRow(12)).toBe "    current < pivot ? left.push(current) : right.push(current);"
+        expect(editSession.lineForBufferRow(13)).toBe "  }"
+
     describe ".indentSelectedRows()", ->
       beforeEach ->
         editSession.tabLength = 2

src/app/edit-session.coffee

@@ -202,7 +202,8 @@ class EditSession
       maintainPasteboard = true
 
   pasteText: ->
-    @insertText(pasteboard.read()[0], normalizeIndent: true)
+    [text, metadata] = pasteboard.read()
+    @insertText(text, _.extend(metadata ? {}, normalizeIndent: true))
 
   undo: ->
     @buffer.undo(this)

src/app/selection.coffee

@@ -269,8 +269,13 @@ class Selection
   copy: (maintainPasteboard=false) ->
     return if @isEmpty()
     text = @editSession.buffer.getTextInRange(@getBufferRange())
-    text = pasteboard.read()[0] + "\n" + text if maintainPasteboard
-    pasteboard.write(text)
+    if maintainPasteboard
+      [currentText, metadata] = pasteboard.read()
+      text = currentText + '\n' + text
+    else
+      metadata = { indentBasis: @editSession.indentationForBufferRow(@getBufferRange().start.row) }
+
+    pasteboard.write(text, metadata)
 
   fold: ->
     range = @getBufferRange()