repos: Fix relative path for repos

If a repo path is relative, append the kas work dir to it.

Background: The path ends up in bblayers.conf

Without this change the following example will fail:

--------------------------------------------------------
header:
     version: 4
machine: qemux86
repos:
     poky:
         url: "https://git.yoctoproject.org/git/poky"
         refspec: "rocko"
         path: "thirdparty/poky"
         layers:
             meta:
             meta-poky:
--------------------------------------------------------

Signed-off-by: Georg Lutz <georg@georglutz.de>

kas/repos.py

@@ -96,7 +96,12 @@ class Repo:
             url = path
             disable_operations = True
         else:
-            path = path or os.path.join(config.kas_work_dir, name)
+            if path is None:
+                path = os.path.join(config.kas_work_dir, name)
+            else:
+                if not os.path.isabs(path):
+                    # Relative pathes are assumed to start from work_dir
+                    path = os.path.join(config.kas_work_dir, path)
 
         if typ == 'git':
             return GitRepo(url, path, refspec, layers, disable_operations)