+which will force a total index re-build from the tree pointed to by HEAD
+(it resets the index contents to HEAD, and then the git-update-cache
+makes sure to match up all index entries with the checked-out files).
+
+The above can also be written as simply
+
+ git reset
+
+and in fact a lot of the common git command combinations can be scripted
+with the "git xyz" interfaces, and you can learn things by just looking
+at what the git-*-script scripts do ("git reset" is the above two lines
+implemented in "git-reset-script", but some things like "git status" and
+"git commit" are slightly more complex scripts around the basic git
+commands).