Libguestfs - Aug 2015 - [PATCH] dib: handle unsetting functions in environment

When I turned off debug and actually looked at the normal output, this
is a bit noisy...

[jeckersb@baozi libguestfs]$ ./run virt-dib -B ~/git/diskimage-builder/lib/
--element-path ~/git/diskimage-builder/elements/ fedora-minimal
[   0.0] Elements: base fedora-minimal
[   0.0] Expanded elements: base dib-init-system dib-run-parts fedora-minimal
install-types package-installs pkg-map redhat-common rpm-distro yum yum-minimal
[   0.0] Carried environment variables:
[   0.0] Preparing auxiliary data
[   0.2] Running: extra-data.d/10-create-pkg-map-dir
/tmp/dib.dQ8W3Z/aux/fake-bin/sudo: line 39: unset: `BASH_FUNC_module()': not
a valid identifier
/tmp/dib.dQ8W3Z/aux/fake-bin/sudo: line 39: unset: `BASH_FUNC_scl()': not a
valid identifier
/tmp/dib.dQ8W3Z/aux/fake-bin/sudo: line 39: unset: `BASH_FUNC_module()': not
a valid identifier
/tmp/dib.dQ8W3Z/aux/fake-bin/sudo: line 39: unset: `BASH_FUNC_scl()': not a
valid identifier
/tmp/dib.dQ8W3Z/aux/fake-bin/sudo: line 39: unset: `BASH_FUNC_module()': not
a valid identifier
/tmp/dib.dQ8W3Z/aux/fake-bin/sudo: line 39: unset: `BASH_FUNC_scl()': not a
valid identifier
[   0.2] Running: extra-data.d/50-store-build-settings
[   0.2] Running: extra-data.d/99-enable-install-types
[   0.2] Running: extra-data.d/99-squash-package-install
[   0.3] Running: extra-data.d/99-yum-repo-conf
[   0.3] Opening the disks
...etc...

So this one instead dumps the noise into /dev/null

If a function name, with its trailing parentheses, is in the
environment , trying to unset it will error out with a message of "not
a valid identifier".  In this case, try to unset it again with the -f
option which can handle the parentheses in the supplied identifier.
---
 dib/dib.ml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/dib/dib.ml b/dib/dib.ml
index d730527..519da51 100644
--- a/dib/dib.ml
+++ b/dib/dib.ml
@@ -283,7 +283,7 @@ if [ -z \"$preserve_env\" ]; then
   for envvar in `env | grep '^\\w' | cut -d= -f1`; do
     case \"$envvar\" in
       PATH | USER | USERNAME | HOSTNAME | TERM | LANG | HOME | SHELL | LOGNAME
) ;;
-      *) unset $envvar ;;
+      *) unset $envvar || unset -f $envvar;;
     esac
   done
 fi
-- 
2.4.3

It helps if I actually include the amended commit...