Revert "hm: remove watchman"

This reverts commit 821a964af5.

shared/home/default.nix

@@ -5,7 +5,26 @@
   email,
   devEnvironment,
   ...
-}: {
+}: let
+  queryWatchman = with pkgs; let
+    # TODO: this is a perl script which needs $LOCALE_ARCHIVE.
+    # As of writing, I have this in my ~/.bashrc:
+    # export LOCALE_ARCHIVE=/usr/lib/locale/locale-archive
+    fsmon =
+      runCommand "fsmonitor-watchman"
+      {
+        src = "${git}/share/git-core/templates/hooks/fsmonitor-watchman.sample";
+        buildInputs = [gnused];
+      } ''
+        sed -e 's@^#!/usr/bin/perl@#!${perl}@' $src > $out
+        chmod +x $out
+      '';
+  in
+    writeShellScript "query-watchman" ''
+      export PATH=${pkgs.watchman}/bin:$PATH
+      exec ${fsmon.outPath} "$@"
+    '';
+in {
   home = {
     inherit stateVersion;
 
@@ -75,6 +94,8 @@
     userName = "Motiejus Jakštys";
     aliases.yolo = "commit --amend --no-edit -a";
     extraConfig = {
+      core.fsmonitor = queryWatchman.outPath;
+      core.untrackedcache = true;
       rerere.enabled = true;
       pull.ff = "only";
       merge.conflictstyle = "diff3";