apycot #2551840 narvalbot shouldn't run plans with umask=077 [done]

We have problems due to the restrictive umask because:
- checking out a hg repo obeys umask
- distutils sdist uses hard links from the source tree when preparing its
release tree (and thus uses the same permissions)
- distutils sdist doesn't force sane file permissions when it creates a tarball
- we could work around the above by setting TAR_OPTIONS when calling sdist, but
that would only work with python 2.6 because 2.7 uses the tarfile module
instead of forking tar
We need to do all the above in some executions, so setting umask to 022 in narvalbot seems like the least bad solution...

done in2.2.4
load left0.000
closed by#2b17abd6f7c9 Set umask to 022 instead of the default 077 (closes #2551840)