Created attachment 3444 [details]
The custom.xml used for testing

Below are the steps to reproduce:

1) Remove git from the layers which you are planning to add in the custom.xml
2) Start toaster with the custom.xml. The custom.xml is placed inside the build directory.
3) Build core-image-minimal
4) After that create new custom image with name my-core-image-minimal
5) Add package : gawk
6) Build my-core-image-minimal

Expected : The build should succeed.

Actual Result: The build fails

Log:
(venv)[sujith@sujith build]$ 2016-09-28 14:16:19,758 INFO runbuilds: starting build Project object in progress, environment BuildEnvironment object
2016-09-28 14:16:19,797 DEBUG localhostbecontroller, our git repos are {('git://git.yoctoproject.org/poky', 'HEAD'): [('bitbake', 'bitbake')]}
2016-09-28 14:16:19,797 DEBUG lbc_shellcmmd: (/home/sujith/poky-test) git remote -v
2016-09-28 14:16:19,804 WARNING localhostbecontroller: shellcmd error command: git remote -v 
b'fatal: Not a git repository (or any of the parent directories): .git\n'
2016-09-28 14:16:19,804 INFO Using pre-checked out source for layer {}
2016-09-28 14:16:19,805 DEBUG localhostbecontroller: giturl git://git.yoctoproject.org/poky:HEAD checking out in current directory /home/sujith/poky-test
2016-09-28 14:16:19,805 DEBUG lbc_shellcmmd: (/home/sujith/poky-test) git remote -v
2016-09-28 14:16:19,811 WARNING localhostbecontroller: shellcmd error command: git remote -v 
b'fatal: Not a git repository (or any of the parent directories): .git\n'
2016-09-28 14:16:19,812 DEBUG localhostbecontroller: selected poky dir name /home/sujith/poky-test
2016-09-28 14:16:19,812 DEBUG localhostbecontroller: localdirpath expected '/home/sujith/poky-test/bitbake'
2016-09-28 14:16:19,812 DEBUG localhostbecontroller: current layer list [] 
2016-09-28 14:16:19,827 ERROR runbuilds: Error launching build expected string or buffer
Traceback (most recent call last):
  File "/home/sujith/poky-test/bitbake/lib/toaster/bldcontrol/management/commands/runbuilds.py", line 63, in schedule
    "%d:%d" % (br.pk, bec.be.pk))
  File "/home/sujith/poky-test/bitbake/lib/toaster/bldcontrol/localhostbecontroller.py", line 274, in triggerBuild
    layers = self.setLayers(bitbake, layers, targets)
  File "/home/sujith/poky-test/bitbake/lib/toaster/bldcontrol/localhostbecontroller.py", line 235, in setLayers
    br_layer_base_recipe.commit),
  File "/home/sujith/poky-test/bitbake/lib/toaster/bldcontrol/localhostbecontroller.py", line 78, in getGitCloneDirectory
    return "_toaster_clones/_%s_%s" % (re.sub('[:/@%]', '_', url), branch)
  File "/home/sujith/poky-test/venv/lib64/python3.4/re.py", line 179, in sub
    return _compile(pattern, flags).sub(repl, string, count)
TypeError: expected string or buffer

(venv)[sujith@sujith build]$