main: pass the right error variable

(cherry picked from commit ac10f7e)
(cherry picked from commit 01dce7e)

src/core/main.c

@@ -2530,7 +2530,7 @@ static void setenv_manager_environment(void) {
 
                 r = putenv_dup(*p, true);
                 if (r < 0)
-                        log_warning_errno(errno, "Failed to setenv \"%s\", ignoring: %m", *p);
+                        log_warning_errno(r, "Failed to setenv \"%s\", ignoring: %m", *p);
         }
 }