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.

diff -r acd8075edac9 b
--- /dev/null
+++ b/b
@@ -0,0 +1,1 @@
+123
diff -r acd8075edac9 b
--- /dev/null
+++ b/b
@@ -0,0 +1,1 @@
+123
diff -r acd8075edac9 a
--- a/a
+++ b/a
@@ -0,0 +1,1 @@
+foo
diff -r acd8075edac9 b
--- /dev/null
+++ b/b
@@ -0,0 +1,1 @@
+123