bigfoot, paragraph-style footnotes, and premature page breaks

Question

When using the bigfoot package and its paragraph-style footnotes, sometimes page breaks are inserted in the main text although there's room for another line. I've nailed down the problem in the following MWE -- uncommenting the third (and rather short) footnote will move one line of the main text to page 2. I'd like to know what causes this behaviour and would be glad about a solution (preamble or in-text workaround for individual pages).

\documentclass{article}

\usepackage[english]{babel}
\usepackage{blindtext}

\usepackage[scale=0.635]{geometry}

\usepackage{bigfoot}
\DeclareNewFootnote[para]{default}

\begin{document}

This is the first paragraph. It only encompasses two lines. Some more text
without a meaning so that the former statement becomes true.
\footnote{A footnote.}

\blindtext
\footnote{Another one.}

\blindtext
% \footnote{A crucial footnote.}% uncommenting this will move one line
%     of the main text to page 2

\blindtext

\blindtext

\blindtext

\end{document}

Example output -- bottom of page 1:

Output after uncommenting the "crucial" footnote:

A crude workaround is to use \enlargethispage for problematic pages (in my MWE, any value between 1.7pt and 1.75pt for page 1 will do). (See this answer for details about \enlargethispage.) However, I'd very much prefer a solution that doesn't change the margins of individual pages.

Answer 1

Well, there are good news and bad news.

The good news is that version 2.0 of bigfoot indeed does away with premature page breaks. This is true for the MWE in my above question, and it is also true for a larger test document containing about a dozen short footnotes per page. I thank egreg for pointing out the bigfoot update.

The bad news is that my larger test document revealed that bigfoots paragraph-style footnotes seem to be plagued by a different typesetting problem, namely, occasionally overfull pages as described in section 9 of the manyfoot documentation:

The algorithm used for calculation the vertical space occupied with para-footnotes has one serious disadvantage. It cannot exactly calculate how many vertical space the collected para-footnotes will occupy because the formatting of such footnotes in vertical box is applied in the output routine after TEX decides on page breaking. For example, if collected para-footnotes occupy 2.25 lines, the algorithm reserves the vertical space of 2.25\normalbaselineskip for them, but when such footnotes will be formatted in vbox, 3 lines will be necessary of course. This is the reason why the use of para-footnotes can lead to page overfull.

In my larger test document, in about one of three pages the footnote block spills up to 5pt (one half of the line height) into the bottom margin. The deviation is large enough to be spotted by a non-trained eye. Also note that the crude workaround mentioned in the manyfoot documentation (adjusting the default space reserved for footnotes with a new \ExtraParaSkip macro) is not available when using bigfoot.