Allow fetch-manifest to have override'able remotes

Example usage...

./foo/fetch-manifest.rb foo/default.xml foo/override.xml

Change-Id: I01d3d8d8c927fb90e2526943eb81bf57e3c8587c
Reviewed-on: http://review.membase.org/5184
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>

fetch-manifest.rb

@@ -4,7 +4,9 @@
 require 'rubygems'
 require 'rake'
 
-path = ARGV[0] # Example: "some/repo/manifest/default.xml"
+path = ARGV[0] # Required. Example: some/repo/manifest/default.xml
+more = ARGV[1] # Optional. Example: some/override.xml
+
 root = REXML::Document.new(File.new(path)).root
 
 default = root.get_elements("//default")[0]
@@ -14,6 +16,15 @@
   remotes[remote.attributes['name']] = remote
 end
 
+# An override.xml file can be useful to specify different remote
+# servers, such as to a closer, local git mirror.
+#
+if more
+  REXML::Document.new(File.new(more)).root.each_element("//remote") do |remote|
+    remotes[remote.attributes['name']] = remote
+  end
+end
+
 root.each_element("//project") do |project|
   name     = project.attributes['name']
   path     = project.attributes['path']

override.xml

@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<manifest>
+  <remote name="membase"
+          fetch="git://10.1.1.210/"
+          review="review.membase.org" />
+  <remote name="couchbase"
+          fetch="git://10.1.1.210/"
+          review="review.membase.org" />
+  <remote name="apache"
+          fetch="git://github.com/apache/" />
+</manifest>