Try to fetch the element as deleted if initial access failed

The reference to the object might be already deleted by when the
request is failing. plus setting deleted=0 is rejected by the API.
So try with deleted=1 if and only if the previous access failed.

lib/obs.py

@@ -148,12 +148,28 @@ class OBS:
         ]
 
     def _download(self, project, package, name, revision):
+        # the object might be deleted but we can only pass deleted=1
+        # if it is actually deleted
+        deleted = 0
+        while deleted < 2:
+            url = osc.core.makeurl(
+                self.url,
+                ["source", project, package, urllib.parse.quote(name)],
+                {"rev": revision, "expand": 1, "deleted": deleted if deleted else ()},
+            )
+            try:
+                osc.core.http_request("HEAD", url)
+                break
+            except Exception:
+                pass
+            deleted += 1
+
         url = osc.core.makeurl(
-            self.url,
-            ["source", project, package, urllib.parse.quote(name)],
-            {"rev": revision, "expand": 1},
-        )
-        return osc.core.http_GET(url)
+                self.url,
+                ["source", project, package, urllib.parse.quote(name)],
+                {"rev": revision, "expand": 1, "deleted": 1 if deleted else ()},
+            )
+        return osc.core.http_request("GET", url)
 
     def download(
         self,