util: drop write_content_size=True This is now the default in python-zstandard 0.9. While we're here, also add a comment about the ability to drop frame magic to save space. Differential Revision: https://phab.mercurial-scm.org/D3199

zstandard: vendor python-zstandard 0.9.0 This was just released. It features a number of goodies. More info at https://gregoryszorc.com/blog/2018/04/09/release-of-python-zstandard-0.9/. The clang-format ignore list was updated to reflect the new source of files. The project contains a vendored copy of zstandard 1.3.4. The old version was 1.1.3. One of the changes between those versions is that zstandard is now dual licensed BSD + GPLv2 and the patent rights grant has been removed. Good riddance. The API should be backwards compatible. So no changes in core should be needed. However, there were a number of changes in the library that we'll want to adapt to. Those will be addressed in subsequent commits. Differential Revision: https://phab.mercurial-scm.org/D3198

revlog: reset _nodepos after strip When using the pure revlog parser, _nodepos is used to keep track of the position during index scanning in the non-cached cache. If it is out of bounds, BaseIndexObject._fix_index will assert. Since strip can actually remove the position scanned last, make sure to reset it. Add an assertion in the place where the invariance is clearer. Differential Revision: https://phab.mercurial-scm.org/D3188

paper: make all source lines have the same minimum height Empty source lines in paper and coal themes used to have smaller height than every other line (because of the way line numbers are shown and because they are using smaller font). This wasn't very noticeable before the follow lines functionality was added, but after that just using the follow-lines button to select a block of code with empty lines would demonstrate the fact that empty lines didn't have enough height - there were white "gaps" in the selection block. Since this problem occurs when lines don't have any content inside, let's create a pseudo-element (it's unselectable because of that) which still doesn't have any content, but fills up empty lines to 100% of their height because of display: inline-block. This is the most natural way to solve this annoyance that I've found so far. Hardcoding height isn't useful because we can have wrapped lines, in which case multiple lines of text need to fit into a single <span>. Setting min-height or line-height doesn't remove the gaps when viewed in Chromium.