Here is a patch to create a python method gst.debug_log(), which has parameters very similar to the C function gst_debug_log(). It differs from gst.debug() in that it lets you specify the level, filename, function, and line number.

It solves the problem that if the Python code uses a separate logging system (such as Python's logging module), we can make the logging system redirect output to Gstreamer but the filename, function and line number that is printed will always be those from the logging system, and not from where the message originated. For example:

def mylog(message):
  print message
  gst.debug(message)

def foo():
  mylog("enter foo")
  # do something
  mylog("leave foo")

With the above code, you will see this in the gstreamer log:
0:00:00.167498608  1024  0x9c931d8 DEBUG   python log.py:3:mylog: enter foo
0:00:00.167498700  1024  0x9c931d8 DEBUG   python log.py:3:mylog: leave foo

All debug messages will have the same filename, function and line number.

I have attached a patch from current git, as well as a log.py file which demonstrates a use case of the patch with Python's logging module.