[entropy.const] make possible to enable entropy.server community repositories mode by setting ETP_COMMUNITY_MODE

libraries/entropy/const.py

@@ -208,6 +208,11 @@ def const_default_settings(rootdir):
         with open(cmdline_file, "r") as cmdline_f:
             cmdline = cmdline_f.readline().strip().split()
 
+    def _default_community_repo_mode():
+        if os.getuid() != 0:
+            return False
+        return os.getenv("ETP_COMMUNITY_MODE", False)
+
     etpConst.clear()
     my_const = {
         'logging': {
@@ -216,7 +221,7 @@ def const_default_settings(rootdir):
         },
         'server_repositories': {},
         'community': {
-            'mode': False,
+            'mode': _default_community_repo_mode(),
         },
         'cmdline': cmdline,
         'backed_up': {},