OBS: latest: handle "version is None"

Fix the Osmocom_OBS_latest job, which currently fails on git
repositories where no tagged release can be found with:

    File "/obs/lib/debian.py", line 96, in transform_version
      if "osmo-epdg-" in version:
         ^^^^^^^^^^^^^^^^^^^^^^^
  TypeError: argument of type 'NoneType' is not iterable

Fixes: 9b36d2a8 ("OBS: fix up-to-date check for strongswan-epdg")
Change-Id: I69cb884d499d1f6a8cae4b4585d31b5bc095fd6e
---
M scripts/obs/lib/debian.py
1 file changed, 21 insertions(+), 0 deletions(-)

diff --git a/scripts/obs/lib/debian.py b/scripts/obs/lib/debian.py
index 68459c8..85fcc5f 100644
--- a/scripts/obs/lib/debian.py
+++ b/scripts/obs/lib/debian.py
@@ -93,6 +93,9 @@
 
 
 def transform_version(version):
+    if version is None:
+        return None
+
     if "osmo-epdg-" in version:
         version = f"{version.replace('osmo-epdg-', '', 1)}-osmo-epdg"
 

