Bups fails backup on linux mint about bups HOT 6 CLOSED

$ which bup
/additional/bin/bin/bup

Python 2.7.12 (default, Nov 19 2016, 06:48:10) 
[GCC 5.4.0 20160609] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> from subprocess import PIPE, Popen, call
>>> Popen("bup")
<subprocess.Popen object at 0x7f5f4721d210>
>>> Usage: bup [-?|--help] [-d BUP_DIR] [--debug] [--profile] <command> [options...]

Common commands:
    fsck       Check backup sets for damage and add redundancy information
    ftp        Browse backup sets using an ftp-like client
    fuse       Mount your backup sets as a filesystem
    help       Print detailed help for the given command
    index      Create or display the index of files to back up
    on         Backup a remote machine to the local one
    restore    Extract files from a backup set
    save       Save files into a backup set (note: run "bup index" first)
    tag        Tag commits for easier access
    web        Launch a web server to examine backup sets

Other available commands:
    bloom                drecurse             import-rsnapshot     ls                   midx                 prune-older          split                                     
    cat-file             gc                   init                 margin               mux                  random               tick                                      
    daemon               import-duplicity     join                 memtest              newliner             rm                   version                                   
    damage               import-rdiff-backup  list-idx             meta                 on--server           server               xstat                                     

See 'bup help COMMAND' for more information on a specific command.

>>> Popen("bup",env={})
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python2.7/subprocess.py", line 711, in __init__
    errread, errwrite)
  File "/usr/lib/python2.7/subprocess.py", line 1343, in _execute_child
    raise child_exception
OSError: [Errno 2] No such file or directory
>>> import os
>>> env={}
>>> env['PATH'] = os.environ['PATH']
>>> Popen("bup",env=env)
<subprocess.Popen object at 0x7f5f4721d6d0>
>>> Usage: bup [-?|--help] [-d BUP_DIR] [--debug] [--profile] <command> [options...]

Common commands:
    fsck       Check backup sets for damage and add redundancy information
    ftp        Browse backup sets using an ftp-like client
    fuse       Mount your backup sets as a filesystem
    help       Print detailed help for the given command
    index      Create or display the index of files to back up
    on         Backup a remote machine to the local one
    restore    Extract files from a backup set
    save       Save files into a backup set (note: run "bup index" first)
    tag        Tag commits for easier access
    web        Launch a web server to examine backup sets

Other available commands:
    bloom                drecurse             import-rsnapshot     ls                   midx                 prune-older          split                                     
    cat-file             gc                   init                 margin               mux                  random               tick                                      
    daemon               import-duplicity     join                 memtest              newliner             rm                   version                                   
    damage               import-rdiff-backup  list-idx             meta                 on--server           server               xstat                                     

See 'bup help COMMAND' for more information on a specific command.