Please describe the problem:
While hacking on some code, we figured it would be useful to dump a pipeline
into XML and to then run that XML through gst-xmllaunch. This provides a nice
way of checking if the pipeline works independent of the rest of the application
code.

To test this I used the following script:

#!/usr/bin/python
import pygst
pygst.require("0.10")
import gst
import gtk

class Main:
	def __init__(self):
		self.pipe = "audiotestsrc ! alsasink"
		self.bin = gst.parse_launch(self.pipe)
		
		gst.xml_write_file(self.bin, open("sinesrc.xml", "w"))
		
		self.bin.set_state(gst.STATE_PLAYING)

start=Main()
gtk.main()

The sinesrc.xml file that it spits out is this:

<?xml version="1.0"?>
<gstreamer xmlns:gst="http://gstreamer.net/gst-core/1.0/">
  <gst:element>
    <gst:name>pipeline0</gst:name>
    <gst:type>pipeline</gst:type>
    <gst:param>
      <gst:name>name</gst:name>
      <gst:value>pipeline0</gst:value>
    </gst:param>
    <gst:param>
      <gst:name>delay</gst:name>
      <gst:value>0</gst:value>
    </gst:param>
    <gst:param>
      <gst:name>auto-flush-bus</gst:name>
      <gst:value>TRUE</gst:value>
    </gst:param>
    <gst:children>
      <gst:element>
        <gst:name>alsasink0</gst:name>
        <gst:type>alsasink</gst:type>
        <gst:param>
          <gst:name>name</gst:name>
          <gst:value>alsasink0</gst:value>
        </gst:param>
        <gst:param>
          <gst:name>preroll-queue-len</gst:name>
          <gst:value>0</gst:value>
        </gst:param>
        <gst:param>
          <gst:name>sync</gst:name>
          <gst:value>TRUE</gst:value>
        </gst:param>
        <gst:param>
          <gst:name>max-lateness</gst:name>
          <gst:value>-1</gst:value>
        </gst:param>
        <gst:param>
          <gst:name>qos</gst:name>
          <gst:value>FALSE</gst:value>
        </gst:param>
        <gst:param>
          <gst:name>buffer-time</gst:name>
          <gst:value>200000</gst:value>
        </gst:param>
        <gst:param>
          <gst:name>latency-time</gst:name>
          <gst:value>10000</gst:value>
        </gst:param>
        <gst:param>
          <gst:name>provide-clock</gst:name>
          <gst:value>TRUE</gst:value>
        </gst:param>
        <gst:param>
          <gst:name>device</gst:name>
          <gst:value>default</gst:value>
        </gst:param>
        <gst:param>
          <gst:name>device-name</gst:name>
          <gst:value/>
        </gst:param>
        <gst:pad>
          <gst:name>sink</gst:name>
          <gst:peer>audiotestsrc0.src</gst:peer>
        </gst:pad>
      </gst:element>
      <gst:element>
        <gst:name>audiotestsrc0</gst:name>
        <gst:type>audiotestsrc</gst:type>
        <gst:param>
          <gst:name>name</gst:name>
          <gst:value>audiotestsrc0</gst:value>
        </gst:param>
        <gst:param>
          <gst:name>blocksize</gst:name>
          <gst:value>4096</gst:value>
        </gst:param>
        <gst:param>
          <gst:name>num-buffers</gst:name>
          <gst:value>-1</gst:value>
        </gst:param>
        <gst:param>
          <gst:name>typefind</gst:name>
          <gst:value>FALSE</gst:value>
        </gst:param>
        <gst:param>
          <gst:name>samplesperbuffer</gst:name>
          <gst:value>1024</gst:value>
        </gst:param>
        <gst:param>
          <gst:name>wave</gst:name>
          <gst:value>0</gst:value>
        </gst:param>
        <gst:param>
          <gst:name>freq</gst:name>
          <gst:value>440.000000</gst:value>
        </gst:param>
        <gst:param>
          <gst:name>volume</gst:name>
          <gst:value>1.000000</gst:value>
        </gst:param>
        <gst:param>
          <gst:name>is-live</gst:name>
          <gst:value>FALSE</gst:value>
        </gst:param>
        <gst:param>
          <gst:name>timestamp-offset</gst:name>
          <gst:value>0</gst:value>
        </gst:param>
        <gst:pad>
          <gst:name>src</gst:name>
          <gst:peer>alsasink0.sink</gst:peer>
        </gst:pad>
      </gst:element>
    </gst:children>
  </gst:element>
</gstreamer>

When I feed this file into gst-xmllaunch-0.10 it doesnt work, and this is the
output:

jono@forge:~/pythontests$ gst-xmllaunch-0.10 sinesrc.xml
Setting pipeline to PAUSED ...
Pipeline is PREROLLING ...
ERROR: from element /pipeline0/audiotestsrc0: Internal data flow error.
Additional debug info:
gstbasesrc.c(1479): gst_base_src_loop (): /pipeline0/audiotestsrc0:
streaming task paused, reason not-linked
ERROR: pipeline doesn't want to preroll.
Setting pipeline to NULL ...
FREEING pipeline ...

There is no audio.

Steps to reproduce:
1. Follow the above steps.
2. 
3. 


Actual results:
The pipeline doesn't work.

Expected results:
The pipeline is executed correctly.

Does this happen every time?
Tested with two different pipelines that I know work.

Other information: