non-file tasks now always report current time as timestamp

doc/release_notes/rake-10.0.0.rdoc

@@ -66,6 +66,16 @@ there are a number of features missing:
 * The deprecated <tt>rake/gempackagetask.rb</tt> library has been
   removed. Gem supplies its own package task now.
 
+There is one small behavioral change:
+
+* Non-file tasks now always report the current time as their time
+  stamp. This is different from the previous behavior where non-file
+  tasks reported current time only if there were no prerequisites, and
+  the max prerequisite timestamp otherwise. This lead to inconsistent
+  and surprising behavior when adding prerequisites to tasks that in
+  turn were prequisites to file tasks. The new behavior is more
+  consistent and predictable.
+
 == Changes (from 0.9.3)
 
 Since Rake 10 includes the changes from the last version of Rake 9,

lib/rake/task.rb

@@ -237,7 +237,7 @@ def needed?
     # Timestamp for this task.  Basic tasks return the current time for their
     # time stamp.  Other tasks can be more sophisticated.
     def timestamp
-      prerequisite_tasks.collect { |pre| pre.timestamp }.max || Time.now
+      Time.now
     end
 
     # Add a description to the task.  The description can consist of an option

test/test_rake_file_task.rb

@@ -59,7 +59,7 @@ def test_file_times_new_depend_on_regular_task_timestamps
 
     task(name => :phony)
 
-    assert ! t1.needed?, "unless the non-file task has a timestamp"
+    assert t1.needed?, "unless the non-file task has a timestamp"
   end
 
   def test_file_times_old_depends_on_new
@@ -83,7 +83,7 @@ def test_file_depends_on_task_depend_on_file
 
     Task[:obj].invoke
     Task[NEWFILE].invoke
-    assert ! @runs.include?(NEWFILE)
+    assert @runs.include?(NEWFILE)
   end
 
   def test_existing_file_depends_on_non_existing_file

test/test_rake_task.rb

@@ -238,7 +238,7 @@ def test_timestamp_returns_latest_prereq_timestamp
     def b.timestamp() Time.now + 10 end
     def c.timestamp() Time.now + 5 end
 
-    assert_in_delta now + 10, a.timestamp, 0.1, 'computer too slow?'
+    assert_in_delta now, a.timestamp, 0.1, 'computer too slow?'
   end
 
   def test_always_multitask