This option, when added via
  TESTS_ENVIRONMENT = [...] $(top_builddir)/run --test
allows us to run the tests and only print the full output (including
debugging etc) when the test fails.

Old KVM can't add /dev/null readonly.  Treat /dev/null as a special
case.

We also fix a few tests where /dev/null was being used with
format=qcow2.  This was always incorrect behaviour, but qemu appears
to tolerate it.

Old versions of libvirt allowed you to define disks like this:

    <disk type='file' device='disk'>
      <driver name='qemu'/>
      ...

Since the <driver> element does not have a 'type' attribute (which
defines the format), we are supposed to do autodetection, so the
format should be undefined.

However what actually happened was that the code in
Sys::Guestfs::Lib::open_guest received format as an empty string from
the xpath query, causing libguestfs to give an error.

If the xpath query returns the format as an empty string, undefine it.

Originally this state was intended so that in some way you could find
out if the appliance was running a command.  However there was never a
thread-safe way to access the state of the handle, so in effect you
could never do anything useful safely with this information.

This commit completely removes the BUSY state.

The only visible change is to the guestfs_is_busy API.  Previously you
could never call this safely from another thread.  If you called it
from the same thread it would always return false (since the current
thread can't be running a libguestfs command at that point by
definition).  Now it always returns false.

I noticed some uses of ${srcdir} in shell scripts.
That is almost always better written as $srcdir.
The patch below converts most such variable references.
Here are the few remaining candidates:

$ git grep -i -E '\$\{[a-zA-Z_0-9]+\}'|grep -v Makefile.in.in
configure.ac:        JAR_INSTALL_DIR=\${prefix}/share/java
configure.ac:        JNI_INSTALL_DIR=\${libdir}
debian/rules:   for TEST in ${DEBIAN_SKIP_TEST}; do \
debian/rules:#          mv $${mod} $$(dirname $${mod})/libguestfsmod.so; \
java/Makefile.am:libguestfs_jar_DATA = libguestfs-${VERSION}.jar
java/Makefile.am:libguestfs-${VERSION}.jar: $(libguestfs_jar_class_files)
perl/lib/Sys/Guestfs/Lib.pm:                      "-f", '${Package} ${Version} ${Architecture} ${Status}\n',
perl/typemap:            croak (\"${Package}::$func_name(): called on a closed handle\");
perl/typemap:        croak (\"${Package}::$func_name(): $var is not a blessed HV reference\");
tests/data/Makefile.am:   echo "$${i}abcdefghijklmnopqrstuvwxyz"; \

We could change all of those, too, except the ones in configure.ac
and Makefile.am, since they refer to Make variables.  Even those
should be changed, but to use the preferred Makefile notation:
$(prefix), $(libdir), $(VERSION).

>From a86770ecd45666232a94d76c8725c8f9b1c76e3a Mon Sep 17 00:00:00 2001
From: Jim Meyering <meyering@redhat.com>
Date: Mon, 23 Jan 2012 11:15:12 +0100
Subject: [PATCH libguestfs] maint: use $var notation rather than ${var} when
 possible

The only case to avoid in a shell script is when the byte after the
"}" is word-constituent, and concatenating it would thus change the
name of the variable.

These changes were induced by running this command:
  git grep -l -i -E '\$\{(srcdir|md)' \
    |xargs perl -pi -e 's/\$\{(srcdir|md)\}($|\w)/\$$1$2/gi'

The "g" was needed because there was one line with two instances.
The "i" is to handle ${SRCDIR}.  The ($|\w) ensures that concatenating
whatever follows the "}" won't change semantics.

* gobject/run-bindtests: Use "$srcdir", not "${srcdir}".
* haskell/run-bindtests: Likewise.
* java/run-bindtests: Likewise.
* ocaml/run-bindtests: Likewise.
* perl/run-bindtests: Likewise.
* python/run-bindtests: Likewise.
* ruby/run-bindtests: Likewise.
* tests/guests/guest-aux/make-debian-img.sh: Likewise, but $SRCDIR.
* tests/guests/guest-aux/make-ubuntu-img.sh: Likewise.
* tests/guests/guest-aux/make-windows-img.sh: Likewise.
* tests/md/test-mdadm.sh: Likewise, but $md.

(Includes fix by RWMJ)

Update all copyright dates to 2012.