^ (Nth parent) and ~ (Nth first ancestor) are infix operators that match
certain ancestors of the set:
set^0
the set
set^1 (also available as set^)
the first parent of every changeset in set
set^2
the second parent of every changeset in set
set~0
the set
set~1
the first ancestor (i.e. the first parent) of every changeset in set
set~2
the second ancestor (i.e. first parent of first parent) of every changeset
in set
set~N
the Nth ancestor (following first parents only) of every changeset in set;
set~N is equivalent to set^1^1..., with ^1 repeated N times.
This adds support for r'...' and r"..." as string literals. Strings
with the "r" prefix will not have their escape characters interpreted.
This is especially useful for grep(), where, with regular string
literals, \number is interpreted as an octal escape code, and \b is
interpreted as the backspace character (\x08).
A query like
head() and (descendants("bad") and not descendants("fix"))
(testing if repo heads are affected by a bug) will abort with a
RepoLookupError if either badrev or fixrev aren't found inside
the repository, which is not very informative.
The new predicate returns an empty set for lookup errors, so
head() and (descendants(present("bad")) and not descendants(present("fix")))
will behave as wanted even if those revisions are not found.