This patch ensures that we propagate errors coming from the lldbinit file trough the command/script interpreter. Before, if you did something like command script import syntax_error.py, and the python file contained a syntax error, lldb wouldn't tell you about it. This changes with the current patch: errors are now propagated by default.
PS: Jim authored this change and I added testing.
Is m_command_source_flags.empty() || Flags(m_command_source_flags.back()).Test(eHandleCommandFlagPrintErrors) better? Not sure.