rn-69: add interview with Philippe Blain

Author: sivaraam

rev_news/drafts/edition-69.md

@@ -29,9 +29,75 @@ This edition covers what happened during the month of October 2020.
 ### Support
 -->
 
-<!---
-## Developer Spotlight:
--->
+## Developer Spotlight: Philippe Blain
+
+* Who are you and what do you do?
+
+ I'm a scientist at the Canadian Center for Meteorological and
+ Environmental Prediction, in Montréal, Québec, Canada. I'm part of the
+ development team for the numerical model we use to predict the movement,
+ growth and melt of sea-ice, the frozen parts of the Arctic and Antarctic
+ oceans. Like most computer models in the field of weather forecasting,
+ this software is written in good old Fortran, and runs on our
+ supercomputers. We use Git extensively to track changes across all
+ layers of our technological stack, and I quickly developed an interest
+ in Git's inner workings.
+
+* What would you name your most important contribution to Git?
+
+ Since I started contributing to the project a little more than one year
+ ago, I've mostly been trying to fix the bugs I encounter in the course
+ of my daily work. So I'm not sure which one of my topics has had the
+ biggest impact on other users. However, I can say that the contribution
+ I'm most proud of is [fixing `git checkout --recurse-submodules`](https://github.com/git/git/compare/d0654dc308b0ba76dd8ed7bbb33c8d8f7aacd783...846f34d3514b81764dea7c2a4851f6187ab31aad)
+ to correctly switch between branches when one branch has nested
+ submodules and the other branch has no submodules at all. I learned
+ enormously during the process of developing this fix, not only about how
+ Git ["unpack trees"](https://github.com/git/git/blob/master/unpack-trees.c)
+ to keep the index, working directory and HEAD consistent, but also how
+[`fork` and `exec`](https://en.wikipedia.org/wiki/Fork%E2%80%93exec)
+ calls work and especially how to debug such spawned process using GDB
+ and LLDB.
+
+* What are you doing on the Git project these days, and why?
+
+ Right now I'm working on a fix to prevent `git checkout
+ --recurse-submodules` from losing uncommitted work in submodules.
+ Although the documentation says this shouldn't happen, I've found a few
+ cases where it does, and since it's never a nice experience to lose
+ work, I'd like to fix that.
+
+* If you could get a team of expert developers to work full time on
+ something in Git for a full year, what would it be?
+
+ Apart from rewriting the whole thing in C++, you mean? Jokes aside, I
+ would like for more work to be put towards better submodule support.
+ There was a colossal effort a couple of years ago to add
+`--recurse-submodules` flags to several Git commands, so that submodules
+ worktrees stay up to date when switching between superproject commits.
+ Unfortunately this effort has died off due to core contributors to the
+ submodule code changing jobs, and some porcelain commands still lack
+ that capability.
+
+* If you could remove something from Git without worrying about
+ backwards compatibility, what would it be?
+
+ I think it's unfortunate that the dot-dot vs. dot-dot-dot syntax mean
+ different things in `git diff` than in the rest of Git commands. It's
+ another one of those tricky things that users have to remember. The fact
+ that `checkout` and `reset` have so many different modes of operation
+ also make them confusing for beginners. The introduction of `git switch`
+ and `git restore` should help with that, though.
+
+* What is your favorite Git-related tool/library, outside of Git itself?
+
+ Since I've heard of it I've been using
+[`diff-so-fancy`](https://github.com/so-fancy/diff-so-fancy#readme) as a
+ way to make Git diffs more easily readable. Apart from that I mostly
+ stick to the Git command line. Recently I discovered
+[`git-crecord`](https://github.com/andrewshadura/git-crecord#readme), an
+ ncurses interface for, among other features, interactive line-by-line
+ staging.
 
 ## Releases