fix regression in serial console handling (bnc#870514)

src/lib/bootloader/serial_console.rb

@@ -37,12 +37,13 @@ class SerialConsole
     # @return [Bootloader::SerialConsole,nil] returns nil if none found,
     #   otherwise instance of SerialConsole
     def self.load_from_kernel_args(kernel_params)
-      console_parameter = kernel_params.parameter("console")
-      return nil unless console_parameter
+      console_parameters = kernel_params.parameter("console")
+      return nil unless console_parameters
 
-      console_parameter = Array(console_parameter)
-      serial_console = console_parameter.find { |p| p =~ /ttyS/ || p =~ /ttyAMA/ }
-      return nil unless serial_console
+      console_parameters = Array(console_parameters)
+      # use only the last parameter (bnc#870514)
+      serial_console = console_parameters.last
+      return nil if serial_console !~ /ttyS/ && serial_console !~ /ttyAMA/
 
       unit = serial_console[KERNEL_PARAM_REGEXP, 2]
       return nil if unit.empty?

test/serial_console_test.rb

@@ -16,6 +16,13 @@
       expect(described_class.load_from_kernel_args(kernel_args)).to eq nil
     end
 
+    # covers bug #870514
+    it "returns nil if serial console configuration is not the last one" do
+      kernel_args = double("KernelArgs", :parameter => ["ttyS1", "tty1"])
+
+      expect(described_class.load_from_kernel_args(kernel_args)).to eq nil
+    end
+
     it "loads configuration if found" do
       kernel_args = double("KernelArgs", :parameter => "ttyS1,4800n8")
       expected_grub_config = "serial --unit=1 --speed=4800 --parity=no --word=8"