pulse api: Retry fetching the result

When a pulse build is interrupted, fetching artifacts fails due to being
unavailable for a short bit. Retry so it fails more cleanly

ci/pulse/api/lib/pulse_build_result.rb

@@ -2,6 +2,7 @@ require "net/http"
 require "uri"
 
 class PulseBuildResult
+  MAX_RETRY_ATTEMPTS = 3
 
   def initialize(pulse_options, build_result, build_messages, build_artifacts)
     @pulse_options = pulse_options
@@ -51,7 +52,7 @@ class PulseBuildResult
 
   def fetch_uri(uri_string, limit = 10)
     raise ArgumentError, 'HTTP redirect too deep' if limit == 0
-    response = Net::HTTP.get_response(URI.parse(uri_string))
+    response = retry_call { Net::HTTP.get_response(URI.parse(uri_string)) }
     case response
     when Net::HTTPSuccess     then response
     when Net::HTTPRedirection then fetch_uri(response['location'], limit - 1)
@@ -60,6 +61,19 @@ class PulseBuildResult
     end
   end
 
+  def retry_call(&block)
+    attempts = 0
+    begin
+      yield
+    rescue Net::HTTPFatalError => error
+      raise error if attempts > MAX_RETRY_ATTEMPTS
+      puts "Got error: #{error} - retry ##{attempts} of #{MAX_RETRY_ATTEMPTS}"
+      attempts += 1
+      sleep (10 * attempts)
+      retry
+    end
+  end
+
   def colorize(message)
     colors = {
       :red => 31,