[merge] run_bzr_subprocess should not remove missing vars

[John Arbash Meinel]

In trying to fix a different bug with Matthieu Moy, I found that
run_bzr_subprocess(env_changes={'foobar':None}) would fail if 'foobar'
did not exist in the environment.

For some reason, I thought del os.environ['foobar'] was safe, even for
missing keys. Anyway, it turns out that you get a KeyError.

So the attached patch contains a test and a fix.

John
=:->

-------------- next part --------------
A non-text attachment was scrubbed...
Name: run_bzr_subprocess_update.patch
Type: text/x-patch
Size: 1743 bytes
Desc: not available
Url : https://lists.ubuntu.com/archives/bazaar/attachments/20060902/b906c778/attachment.bin 
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 254 bytes
Desc: OpenPGP digital signature
Url : https://lists.ubuntu.com/archives/bazaar/attachments/20060902/b906c778/attachment.pgp