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.

adding a
adding b
adding t.h
adding t/x
a
NONEXISTENT: No such file or directory
a
b
t.h
t/x
a: No such file or directory
NONEXISTENT: No such file or directory
b
t.h
t/x
a
NONEXISTENT: No such file in rev ce18e5bc5cd3
a
t/x
b
t.h
% -I/-X with relative path should work
b
t.h
t/x
t/x
t/x