Fix issues with user.update endpoint

User may have nologin shell causing the attempt to run cp in a
subprocess to fail due to failure to su to the user in question (due to
error in pam_open_session()).

After review of history for why we were subprocessing out to perform
this task, I failed to find a compelling reason why we could not simply
use shutil.copytree without switching the user context.

This also fixes a bug whereby home directory was not being saved when
the user tried to switch their home directory to a subdirectory of
their current one.

src/middlewared/middlewared/plugins/account.py

@@ -753,17 +753,14 @@ def do_update(self, app, audit_callback, pk, data):
         # Copy the home directory if it changed
         home_copy = False
         home_old = None
-        if (
-            has_home and
-            'home' in data and
-            data['home'] != user['home'] and
-            not data['home'].startswith(f'{user["home"]}/')
-        ):
+        if has_home and 'home' in data:
+            username = data.get('username', user['username'])
             if had_home:
                 home_copy = True
                 home_old = user['home']
-            if data.get('home_create', False):
-                data['home'] = os.path.join(data['home'], data.get('username') or user['username'])
+
+            if data.get('home_create', False) and not data['home'].endswith(username):
+                data['home'] = os.path.join(data['home'], username)
 
         # After this point user dict has values from data
         user.update(data)
@@ -1283,7 +1280,7 @@ async def setup_local_administrator(self, app, username, password, options):
     @private
     @job(lock=lambda args: f'copy_home_to_{args[1]}')
     async def do_home_copy(self, job, home_old, home_new, username, new_mode, uid):
-        if home_old in DEFAULT_HOME_PATHS:
+        if home_old in DEFAULT_HOME_PATHS or home_old == home_new:
             return
 
         if new_mode is not None:
@@ -1303,11 +1300,7 @@ async def do_home_copy(self, job, home_old, home_new, username, new_mode, uid):
             })
 
         await perm_job.wait()
-
-        command = f"/bin/cp -a {shlex.quote(home_old) + '/' + '.'} {shlex.quote(home_new + '/')}"
-        do_copy = await run(["/usr/bin/su", "-", username, "-c", command], check=False)
-        if do_copy.returncode != 0:
-            raise CallError(f"Failed to copy homedir [{home_old}] to [{home_new}]: {do_copy.stderr.decode()}")
+        shutil.copytree(home_old, home_new, dirs_exist_ok=True)
 
     @private
     async def common_validation(self, verrors, data, schema, group_ids, old=None):