Not quite. If you look at server/openerp/tools/yaml_import.py at line 330, you can see a bit more into what's happening. Also in server/openerp/tools/convert.py scattered between lines 817 and 935.

Normally when you import into OpenERP using the standard interface, it will process the entire batch at once, and then commit everything to the database if there are no exceptions raised during the import process. When you set --import-partial, you're committing after every single successful line to be imported. The file that you provide is the name of the file to dump the remaining records that were not imported once the failure occurred, so you won't have to import all of the initial, good records again until you solve every problem in the entire import.

tl;dr: It's not importing from the command line, it's altering how normal importing works.