Clean tools key of obsolete version on next release (esp8266#6258)

Fixes esp8266#6068

Drop from the tools key all version:"1.20.0-26-gb404fb9" entries (which
were pre-2.0.0 and whose entry in platform versions was deleted on last
release).

package/build_boards_manager_package.sh

@@ -156,7 +156,7 @@ new_json=package_esp8266com_index.json
 
 set +e
 # Merge the old and new, then drop any obsolete package versions
-python ../../merge_packages.py $new_json $old_json | python ../../drop_versions.py - platforms 1.6.5-947-g39819f0 2.5.0-beta1 2.5.0-beta2 2.5.0-beta3 2.4.0-rc1 2.4.0-rc2 >tmp && mv tmp $new_json && rm $old_json
+python ../../merge_packages.py $new_json $old_json | python ../../drop_versions.py - tools 1.20.0-26-gb404fb9 >tmp && mv tmp $new_json && rm $old_json
 
 # Verify the JSON file can be read, fail if it's not OK
 set -e

package/drop_versions.py

@@ -4,12 +4,13 @@
 from __future__ import print_function
 import json
 import sys
+from collections import OrderedDict
 
 def load_package(filename):
  if filename == "-":
- pkg = json.load(sys.stdin)['packages'][0]
+ pkg = json.load(sys.stdin, object_pairs_hook=OrderedDict)['packages'][0]
  else:
- pkg = json.load(open(filename))['packages'][0]
+ pkg = json.load(open(filename), object_pairs_hook=OrderedDict)['packages'][0]
  print("Loaded package {0} from {1}".format(pkg['name'], filename), file=sys.stderr)
  print("{0} platform(s), {1} tools".format(len(pkg['platforms']), len(pkg['tools'])), file=sys.stderr)
  return pkg