devtool: fix build env command execution error handling

If we execute an external command, we ought to prepare for the
possibility that it can fail and handle the failure appropriately. We
can especially expect this to happen when running bitbake in this
scenario. Ensure we return the appropriate exit code to the calling
process.

Fixes [YOCTO #7757].

(From OE-Core master rev: 98a716d79bfc5434a5b42d3ca683eab3eea30a41)

(From OE-Core rev: 2791fe9236f7173e6b998cf9b40fe238566ed8ee)

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

scripts/lib/devtool/__init__.py

@@ -43,12 +43,13 @@ def exec_build_env_command(init_path, builddir, cmd, watch=False, **options):
     if watch:
         if sys.stdout.isatty():
             # Fool bitbake into thinking it's outputting to a terminal (because it is, indirectly)
-            cmd = 'script -q -c "%s" /dev/null' % cmd
+            cmd = 'script -e -q -c "%s" /dev/null' % cmd
         return exec_watch('%s%s' % (init_prefix, cmd), **options)
     else:
         return bb.process.run('%s%s' % (init_prefix, cmd), **options)
 
 def exec_watch(cmd, **options):
+    import bb
     if isinstance(cmd, basestring) and not "shell" in options:
         options["shell"] = True
 
@@ -65,7 +66,11 @@ def exec_watch(cmd, **options):
             buf += out
         elif out == '' and process.poll() != None:
             break
-    return buf
+
+    if process.returncode != 0:
+        raise bb.process.ExecutionError(cmd, process.returncode, buf, None)
+
+    return buf, None
 
 def setup_tinfoil():
     import scriptpath