trydiff: use sets, not lists, for containment checks
This only has a noticeable effect on diffs touching A LOT of
files. For example, it takes
hg diff -r FIREFOX_AURORA_30_BASE -r FIREFOX_AURORA_35_BASE
from 1m55.465s to 1m32.354s. That diff has over 50k files.
When Mercurial accepts more than one revision, they may be specified
individually, or provided as a topologically continuous range,
separated by the ":" character.
The syntax of range notation is [BEGIN]:[END], where BEGIN and END are
revision identifiers. Both BEGIN and END are optional. If BEGIN is not
specified, it defaults to revision number 0. If END is not specified,
it defaults to the tip. The range ":" thus means "all revisions".
If BEGIN is greater than END, revisions are treated in reverse order.
A range acts as a closed interval. This means that a range of 3:5
gives 3, 4 and 5. Similarly, a range of 9:6 gives 9, 8, 7, and 6.