util: increase filechunkiter size to 128k util.filechunkiter has been using a chunk size of 64k for more than 10 years, also in years where Moore's law still was a law. It is probably ok to bump it now and perhaps get a slight win in some cases. Also, largefiles have been using 128k for a long time. Specifying that size multiple times (or forgetting to do it) seems a bit stupid. Decreasing it to 64k also seems unfortunate. Thus, we will set the default chunksize to 128k and use the default everywhere.

largefiles: always use filechunkiter when iterating files Before, we would sometimes use the default iterator over large files. That iterator is line based and would add extra buffering and use odd chunk sizes which could give some overhead. copyandhash can't just apply a filechunkiter as it sometimes is passed a genuine generator when downloading remotely.

revset: for x^2, do not take null as a valid p2 revision Since we don't count null p2 revision as a parent, x^2 should never return null even if null is explicitly populated.

revset: make follow() reject more than one start revisions Taking only the last revision is inconsistent because ancestors(set) follows all revisions given, and theoretically follow(startrev=set) == ancestors(set). I'm planning to add a support for multiple start revisions, but that won't fit to the 4.0 time frame. So reject multiple revisions now to avoid future BC. len(revs) might be slow if revs were large, but we don't care since a valid revs should have only one element.

bundle2: only emit compressed chunks if they have data This is similar to 58467204cac0. Not all calls into the compressor return compressed data, as the compressor may buffer compressed output internally. It is cheaper to check for empty chunks than to send empty chunks through the generator. When generating a gzip-v2 bundle of the mozilla-unified repo, this change results in 50,093 empty chunks not being sent through the generator (out of 1,902,996 total input chunks).

color: add some documentation for custom terminfo codes

color: debugcolor should emit the user-defined colors This also fixes a long-standing bug that reversed the sense of the color name and the label used to print it, which was never relevant before.

color: ignore effects missing from terminfo If terminfo mode is in effect, and an effect is used which is missing from the terminfo database, simply silently ignore the request, leaving the output unaffected rather than causing a crash.

color: allow for user-configurable terminfo codes for effects If the entry in the terminfo database for your terminal is missing some attributes, it should be possible to create them on the fly without resorting to just making them a color. This change allows you to have [color] terminfo.<effect> = <code> where <effect> might be something like "dim" or "bold", and <code> is the escape sequence that would otherwise have come from a call to tigetstr(). If an escape character is needed, use "\E". Any such settings will override attributes that are present in the terminfo database.

update: warn if cwd was deleted During update directories are deleted as soon as they have no entries. But if current working directory is deleted then it cause problems in complex commands like 'hg split'. This commit adds a warning that will help users figure the problem faster.