save settings from untrusted config files in a separate configparser This untrusted configparser is a superset of the trusted configparser, so that interpolation still works. Also add an "untrusted" argument to ui.config* to allow querying ui.ucdata. With --debug, we print a warning when we read an untrusted config file, and when we try to access a trusted setting that has one value in the trusted configparser and another in the untrusted configparser.

% init
% commit
adding base
% qnew mqbase
% qrefresh
% qdiff
diff -r 67e992f2c4f3 base
--- a/base
+++ b/base
@@ -1,1 +1,1 @@ base
-base
+patched
% qdiff dirname
diff -r 67e992f2c4f3 base
--- a/base
+++ b/base
@@ -1,1 +1,1 @@ base
-base
+patched