Comment 3 for bug 968756

I just had the same problem.

I realized that this same output error happens because even though I have just uploaded my package (sources), it is still in queue for building, and while this is unfinished, if I try to add the repository with the command add-apt-repository, as it also tries to handle the signatures, it ultimately fails.

So, this is not actually a problem.

My output:

$ sudo add-apt-repository ppa:bruno-braga/termsaver
[sudo] password for bruno:
You are about to add the following PPA to your system:
 A simple text-based terminal screensaver.
 More info: https://launchpad.net/~bruno-braga/+archive/termsaver
Press [ENTER] to continue or ctrl-c to cancel adding it

Exception in thread Thread-1:
Traceback (most recent call last):
  File "/usr/lib/python2.7/threading.py", line 551, in __bootstrap_inner
    self.run()
  File "/usr/lib/python2.7/dist-packages/softwareproperties/ppa.py", line 95, in run
    self.add_ppa_signing_key(self.ppa_path)
  File "/usr/lib/python2.7/dist-packages/softwareproperties/ppa.py", line 117, in add_ppa_signing_key
    "--recv", signing_key_fingerprint])
  File "/usr/lib/python2.7/subprocess.py", line 493, in call
    return Popen(*popenargs, **kwargs).wait()
  File "/usr/lib/python2.7/subprocess.py", line 679, in __init__
    errread, errwrite)
  File "/usr/lib/python2.7/subprocess.py", line 1249, in _execute_child
    raise child_exception
TypeError: execv() arg 2 must contain only strings

If I try to get any other PPA's that are valid, it works just fine:

$ sudo add-apt-repository ppa:dcaro/packages
You are about to add the following PPA to your system:

 More info: https://launchpad.net/~dcaro/+archive/packages
Press [ENTER] to continue or ctrl-c to cancel adding it

Executing: gpg --ignore-time-conflict --no-options --no-default-keyring --secret-keyring /tmp/tmp.ve6b9w6CVX --trustdb-name /etc/apt/trustdb.gpg --keyring /etc/apt/trusted.gpg --primary-keyring /etc/apt/trusted.gpg --keyserver hkp://keyserver.ubuntu.com:80/ --recv 0DCE2702C56392C6B0B97BFC47C98F3E02B8917F
gpg: requesting key 02B8917F from hkp server keyserver.ubuntu.com
gpg: key 02B8917F: public key "Launchpad PPA for David Caro" imported
gpg: Total number processed: 1
gpg: imported: 1 (RSA: 1)