oe imports in central location

Code taken from OE. Allows to import OE modules
without first setting python paths manually.

Signed-off-by: Adriaan Schmidt <adriaan.schmidt@siemens.com>

meta/classes/base.bbclass

@@ -21,6 +21,34 @@
 THISDIR = "${@os.path.dirname(d.getVar('FILE', True))}"
 FILESPATH = "${@base_set_filespath(["${FILE_DIRNAME}/${PF}", "${FILE_DIRNAME}/${P}", "${FILE_DIRNAME}/${PN}", "${FILE_DIRNAME}/files", "${FILE_DIRNAME}"], d)}"
 
+OE_IMPORTS += "os sys time oe.path oe.patch"
+OE_IMPORTS[type] = "list"
+
+def oe_import(d):
+    import sys
+
+    bbpath = d.getVar("BBPATH").split(":")
+    sys.path[0:0] = [os.path.join(dir, "lib") for dir in bbpath]
+
+    def inject(name, value):
+        """Make a python object accessible from the metadata"""
+        if hasattr(bb.utils, "_context"):
+            bb.utils._context[name] = value
+        else:
+            __builtins__[name] = value
+
+    import oe.data
+    for toimport in oe.data.typed_value("OE_IMPORTS", d):
+        try:
+            imported = __import__(toimport)
+            inject(toimport.split(".", 1)[0], imported)
+        except AttributeError as e:
+            bb.error("Error importing OE modules: %s" % str(e))
+    return ""
+
+# We need the oe module name space early (before INHERITs get added)
+OE_IMPORTED := "${@oe_import(d)}"
+
 def get_deb_host_arch():
     import subprocess
     host_arch = subprocess.check_output(

meta/classes/dpkg-base.bbclass

@@ -248,11 +248,6 @@ do_deploy_deb[lockfiles] = "${REPO_ISAR_DIR}/isar.lock"
 do_deploy_deb[dirs] = "${S}"
 
 python do_devshell() {
-    import sys
-
-    oe_lib_path = os.path.join(d.getVar('LAYERDIR_core'), 'lib')
-    sys.path.insert(0, oe_lib_path)
-
     bb.build.exec_func('dpkg_do_mounts', d)
 
     isar_export_proxies(d)

meta/classes/patch.bbclass

@@ -92,11 +92,6 @@ def should_apply(parm, d):
 should_apply[vardepsexclude] = "DATE SRCDATE"
 
 python patch_do_patch() {
-    import sys
-
-    oe_lib_path = os.path.join(d.getVar('LAYERDIR_core'), 'lib')
-    sys.path.insert(0, oe_lib_path)
-
     import oe.patch
 
     patchsetmap = {