What I get

gistfile1.txt

╭─mgoose@mgoose-ml  ~/workspace/fabric ‹457-failure-checking-for-parallel*› 
╰─$ fab                                                                                                                                                  (env: fabric-testing) 1 ↵
Failure: ImportError (cannot import name tasks) ... ERROR
Failure: ImportError (cannot import name state) ... ERROR
Doctest: fabric.operations._shell_escape ... ok
Doctest: fabric.state._AttributeDict ... ok
cd cleans up after itself even in case of an exception ... FAIL
cd() should append arg if non-absolute or overwrite otherwise ... FAIL
Using settings() with a previously nonexistent key should work correctly ... FAIL
settings() should temporarily override env dict with given key/value pair ... FAIL
settings() should temporarily override env dict with given key/value pairS ... FAIL
contains() should return False on bad grep even if stdout isn't empty ... No hosts found. Please specify (single) host string for connection: 
Stopped.