configitems: relax warning about unwanted default value
The original condition was a bit harsh for extension authors since third-party
extensions need to preserve compatibility with older Mercurial versions, where
no defaults would be loaded from the configtable. So let's silence the warning
if the given default value matches, which should be harmless.
$ hg init
$ touch unknown
$ touch a
$ hg add a
$ hg ci -m "1"
$ touch b
$ hg add b
$ hg ci -m "2"
Should show unknown
$ hg status
? unknown
$ hg revert -r 0 --all
removing b
Should show unknown and b removed
$ hg status
R b
? unknown
Should show a and unknown
$ ls
a
unknown