reference: https://idempiere.atlassian.net/browse/IDEMPIERE-2940

1. asume folder contain your idempiere repository is /mnt/data/dev/bitbucket/main-sync/idempiere-experimental

2. asume folder contain new repository is /mnt/data/dev/bitbucket/main-sync/idempiere-reduce

3. active convert extension in your mercurial
https://www.mercurial-scm.org/wiki/ConvertExtension#Configuration

Add the following lines to your .hgrc or to enable the extension :
[extensions]
hgext.convert=

4. run shell command:
IDEMPIERE_ROOT=/mnt/data/dev/bitbucket/main-sync/idempiere-experimental
IDEMPIERE_REDUCE=/mnt/data/dev/bitbucket/main-sync/idempiere-reduce

hg convert --filemap $IDEMPIERE_ROOT/migration/reduce_repository/exclude_file_map.txt $IDEMPIERE_ROOT $IDEMPIERE_REDUCE

5. wait (about 30 miutes) for process finish

6. in new repository do below command to delete latest commit of convert extension 

7. hg rollback --verbose -f

8. upload your new repository to your server or bitbucket