chgserver: do not copy configs set by environment variables

Config set by environment variables have a source like "$ENVNAME". They
should not be copied because they will be recalculated by
rcutil.rccomponents.

mercurial/chgserver.py

@@ -213,8 +213,8 b' def _loadnewui(srcui, args):'
     # stolen from tortoisehg.util.copydynamicconfig()
     for section, name, value in srcui.walkconfig():
         source = srcui.configsource(section, name)
-        if ':' in source or source == '--config':
-            # path:line or command line
+        if ':' in source or source == '--config' or source.startswith('$'):
+            # path:line or command line, or environ
             continue
         newui.setconfig(section, name, value, source)