[PATCH v7 5/8] Acceptance tests: keep a stable reference to the QEMU build dir

[Cleber Rosa <crosa@redhat.com>]

This is related to the the differences in in-tree and out-of-tree
builds in QEMU.  For simplification, <BLD> means my build directory.

Currently, by running a `make check-acceptance` one gets (in
tests/acceptance/avocado_qemu/__init__.py):

   SRC_ROOT_DIR: <BLD>/tests/acceptance/avocado_qemu/../../..

This in itself is problematic, because after the parent directories
are applied, one may be left not with a pointer to the build directory
as intended, but with the location of the source tree (assuming they
differ). Built binaries, such as qemu-img, are of course not there and
can't be found.

Given that a Python '__file__' will contain the absolute path to the
file backing the module, say:

   __file__: <BLD>/tests/acceptance/avocado_qemu/__init__.py

                  |  4  |     3    |      2     |     1     |

A solution is to not "evaluate" the third parent dir (marked as 4
here) because that ends up following the "tests" directory symlink to
the source tree.  In fact, there's no need to keep or evaluate any of
the parent directories, we can just drop the rightmost 4 components,
and we'll keep a stable reference to the build directory (with no
symlink being followed).  This works for either a dedicated build
directory or also a combined source and build tree.

Signed-off-by: Cleber Rosa <crosa@redhat.com>
---
 tests/acceptance/avocado_qemu/__init__.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/acceptance/avocado_qemu/__init__.py b/tests/acceptance/avocado_qemu/__init__.py
index 6618ea67c1..17ce583c87 100644
--- a/tests/acceptance/avocado_qemu/__init__.py
+++ b/tests/acceptance/avocado_qemu/__init__.py
@@ -16,7 +16,7 @@ import tempfile
 
 import avocado
 
-SRC_ROOT_DIR = os.path.join(os.path.dirname(__file__), '..', '..', '..')
+SRC_ROOT_DIR = os.path.dirname(os.path.dirname(os.path.dirname(os.path.dirname(__file__))))
 sys.path.append(os.path.join(SRC_ROOT_DIR, 'python'))
 
 from qemu.machine import QEMUMachine
-- 
2.21.0