cubicweb #4606342 3.19 migration broken for sqlserver [validation pending]

Traceback (most recent call last):
  File "E:\Pylos\pegase\cubicweb\cwctl.py", line 162, in run_arg
    status = cmdmeth(appid)
  File "E:\Pylos\pegase\cubicweb\cwctl.py", line 787, in upgrade_instance
    mih.migrate(vcconf, reversed(toupgrade), self.config)
  File "E:\Pylos\pegase\cubicweb\server\migractions.py", line 178, in migrate
    super(ServerMigrationHelper, self).migrate(vcconf, toupgrade, options)
  File "E:\Pylos\pegase\cubicweb\migration.py", line 166, in migrate
    self.cmd_process_script(join(migrdir, 'bootstrapmigration_repository.py'))
  File "E:\Pylos\pegase\cubicweb\server\migractions.py", line 184, in cmd_process_script
    migrscript, funcname, *args, **kwargs)
  File "E:\Pylos\pegase\cubicweb\migration.py", line 350, in cmd_process_script
    execfile(migrscript, scriptlocals)
  File "E:\Pylos\pegase\cubicweb\misc\migration\bootstrapmigration_repository.py", line 53, in <module>
    sql('ALTER TABLE "entities" DROP COLUMN "mtime"')
  File "E:\Pylos\pegase\cubicweb\server\migractions.py", line 1426, in sqlexec
    cu = self.cnx.system_sql(sql, args)
  File "E:\Pylos\pegase\cubicweb\repoapi.py", line 120, in proxy
    return getattr(clt_cnx._cnx, name)(*args, **kwargs)
  File "E:\Pylos\pegase\cubicweb\server\session.py", line 371, in wrapper
    return func(cnx, *args, **kwargs)
  File "E:\Pylos\pegase\cubicweb\server\session.py", line 381, in check_open
    return func(cnx, *args, **kwargs)
  File "E:\Pylos\pegase\cubicweb\server\session.py", line 1170, in system_sql
    return source.doexec(self, sql, args, rollback=rollback_on_failure)
  File "E:\Pylos\pegase\cubicweb\server\sources\native.py", line 708, in doexec
    cursor.execute(str(query), args)
  File "E:\Pylos\pegase\logilab\database\sqlserver.py", line 109, in execute
    self._cursor.execute(sql)

ProgrammingError: ('42000', "[42000] [Microsoft][ODBC SQL Server Driver][SQL Server]The index 'entities_mtime_idx' is
dependent on column 'mtime'. (5074) (SQLExecDirectW); [42000] [Microsoft][ODBC SQL Server Driver][SQL Server]ALTER TABLE DROP COLUMN mtime failed because one or more objects access this column. (4922)")
priorityimportant
typebug
done in3.19.9
load0.000
load left0.000
closed by<not specified>