revset: prevent crash caused by empty group expression while optimizing "and"
An empty group expression "()" generates None in AST, so the optimizer have
to test it before destructuring a tuple. The error message, "missing argument",
is somewhat obscure, but it should be better than crash.
Test for changeset ba7c74081861
(update dirstate correctly for non-branchmerge updates)
$ hg init a
$ cd a
$ echo a > a
$ hg add a
$ hg commit -m a
$ cd ..
$ hg clone a b
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd a
$ hg mv a b
$ hg commit -m move
$ echo b >> b
$ hg commit -m b
$ cd ../b
$ hg pull ../a
pulling from ../a
searching for changes
adding changesets
adding manifests
adding file changes
added 2 changesets with 2 changes to 1 files
(run 'hg update' to get a working copy)
$ hg update
1 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ cd ..