only run ssh runners if there are files to run remotely, and fix kernel.select to work even better

lib/hydra/master.rb

@@ -72,6 +72,18 @@ module Hydra #:nodoc:
       # default is one worker that is configured to use a pipe with one runner
       worker_cfg = opts.fetch('workers') { [ { 'type' => 'local', 'runners' => 1} ] }
 
+      # if the number of files to run is equal to or less than the count of local
+      # runners, don't even bother with retmote workers.
+      locals, sshes = worker_cfg.partition { |l| l['type'] == 'local' }
+
+      if !locals.empty?
+        if @files.length <= locals.first['runners']
+          sshes = []
+        end
+      end
+
+      worker_cfg = locals + sshes
+
       trace "Initialized"
       trace "  Files:   (#{@files.inspect})"
       trace "  Workers: (#{worker_cfg.inspect})"

lib/hydra/messaging_io.rb

@@ -11,13 +11,14 @@ module Hydra #:nodoc:
       while true
         begin
           raise IOError unless @reader
-          if !@timeout || (result = Kernel.select([@reader], [], [], @timeout))
+          message = nil
+          if result = Kernel.select([@reader], [], [], @timeout)
             message = @reader.gets
           end
           return Message.build(:class => Hydra::Messages::Master::Shutdown) if result == nil
           return nil unless message
           return Message.build(eval(message.chomp))
-        rescue SyntaxError, NameError
+        rescue SyntaxError, NameError, Errno::EBADF
           # uncomment to help catch remote errors by seeing all traffic
           #$stderr.write "Not a message: [#{message.inspect}]\n"
         end