Symlink /usr/sbin to /usr/bin if possible

/usr/local/sbin is also symlinked to /usr/local/bin if possible.

'return 0' is dropped because that causes issues with rpm:
https://github.com/rpm-software-management/rpm/issues/3029

filesystem.spec

@@ -176,7 +176,6 @@ end
 posix.mkdir("/var")
 posix.symlink("../run", "/var/run")
 posix.symlink("../run/lock", "/var/lock")
-return 0
 
 %global sbin_filenames %{lua:
 print('{\\n')
@@ -2283,6 +2282,55 @@ while b do
 
     b = rpm.next_file()
 end
+
+%global merge_scriptlet %{expand:
+--# Symlink /usr/sbin→/usr/bin and /usr/local/sbin→/usr/local/bin if possible
+
+for _,path in pairs({"/usr/sbin", "/usr/local/sbin"}) do
+  st = posix.stat(path)
+  if st and st.type ~= "link" then
+    good = true
+
+    items = rpm.glob(path.."/*")
+    for _,v in pairs(items) do
+      --# rpm.glob() returns the original pattern if match fails :(((
+      if v ~= path.."/*" then
+        st = posix.stat(v)
+
+        if not st then
+          print("Could not stat "..v)
+        else
+          if st.type ~= "link" then
+            print("/usr/sbin cannot be merged, found "..v)
+            good = false
+            break
+          end
+
+          target = posix.readlink(v)
+          name = v:match("^.+/(.+)$")
+          if target ~= "../bin/"..name then
+            print("/usr/sbin cannot be merged, "..v.." points to "..target)
+            good = false
+            break
+          end
+        end
+      end
+    end
+
+    if good then
+      print("All files under "..path.." are symlinks; linking to ./bin...")
+
+      for _,v in pairs(items) do
+        os.remove(v)
+      end
+      os.remove(path)
+      posix.symlink("bin", path)
+      print("...done")
+    end
+  end
+end
+}
+
 %posttrans -p <lua>
 --# we need to restorecon on some dirs created in %pretrans or by other packages
 if posix.access ("/usr/sbin/restorecon", "x") then
@@ -2290,6 +2338,11 @@ if posix.access ("/usr/sbin/restorecon", "x") then
   rpm.execute("/usr/sbin/restorecon", "-r", "/usr/lib/debug")
 end
 
+%merge_scriptlet
+
+%transfiletriggerpostun -p <lua> -- /sbin /usr/sbin
+%merge_scriptlet
+
 %files content
 %dir %{_datadir}/filesystem
 %{_datadir}/filesystem/paths