Added an undocumented JediLoadProject for now

autoload/jedi.vim

@@ -428,6 +428,10 @@ function! jedi#choose_environment(args) abort
     PythonJedi jedi_vim.choose_environment()
 endfun
 
+function! jedi#load_project(args) abort
+    PythonJedi jedi_vim.load_project()
+endfun
+
 function! jedi#py_import_completions(argl, cmdl, pos) abort
     PythonJedi jedi_vim.py_import_completions()
 endfun

plugin/jedi.vim

@@ -54,6 +54,7 @@ endif
 command! -nargs=1 -complete=custom,jedi#py_import_completions Pyimport :call jedi#py_import(<q-args>)
 
 command! -nargs=? -complete=file JediChooseEnvironment :call jedi#choose_environment(<q-args>)
+command! -nargs=? -complete=file JediLoadProject :call jedi#load_project(<q-args>)
 
 
 function! s:jedi_debug_info()

pythonx/jedi_vim.py

@@ -240,6 +240,7 @@ def get_project():
     return project
 
 
+@catch_and_print_exceptions
 def choose_environment():
     args = shsplit(vim.eval('a:args'))
 
@@ -257,11 +258,35 @@ def choose_environment():
     vim_command('noremap <buffer> <CR> :PythonJedi jedi_vim.choose_environment_hit_enter()<CR>')
 
 
+@catch_and_print_exceptions
 def choose_environment_hit_enter():
     vim.vars['jedi#environment_path'] = vim.current.line
     vim_command('bd')
 
 
+@catch_and_print_exceptions
+def load_project():
+    path = vim.eval('a:args')
+    vim.vars['jedi#project_path'] = path
+    env_path = vim_eval("g:jedi#environment_path")
+    if env_path == 'auto':
+        env_path = None
+    if path:
+        try:
+            project = jedi.Project.load(path)
+        except FileNotFoundError:
+            project = jedi.Project(path, environment_path=env_path)
+            project.save()
+    else:
+        project = jedi.get_default_project()
+        path = project.path
+        project.save()
+
+    global _current_project_cache
+    cache_key = dict(project_path=path, environment_path=env_path)
+    _current_project_cache = cache_key, project
+
+
 @catch_and_print_exceptions
 def get_script(source=None):
     jedi.settings.additional_dynamic_modules = [