merge(3p/git): Merge git upstream at v2.26.2

third_party/git/Documentation/git-update-index.txt

@@ -16,6 +16,7 @@ SYNOPSIS
 	     [--chmod=(+|-)x]
 	     [--[no-]assume-unchanged]
 	     [--[no-]skip-worktree]
+	     [--[no-]ignore-skip-worktree-entries]
 	     [--[no-]fsmonitor-valid]
 	     [--ignore-submodules]
 	     [--[no-]split-index]
@@ -113,6 +114,11 @@ you will need to handle the situation manually.
 	set and unset the "skip-worktree" bit for the paths. See
 	section "Skip-worktree bit" below for more information.
 
+
+--[no-]ignore-skip-worktree-entries::
+	Do not remove skip-worktree (AKA "index-only") entries even when
+	the `--remove` option was specified.
+
 --[no-]fsmonitor-valid::
 	When one of these flags is specified, the object name recorded
 	for the paths are not updated. Instead, these options
@@ -426,7 +432,7 @@ specified by the splitIndex.sharedIndexExpire config variable (see
 linkgit:git-config[1]).
 
 To avoid deleting a shared index file that is still used, its
-modification time is updated to the current time everytime a new split
+modification time is updated to the current time every time a new split
 index based on the shared index file is either created or read from.
 
 UNTRACKED CACHE
@@ -543,6 +549,22 @@ The untracked cache extension can be enabled by the
 `core.untrackedCache` configuration variable (see
 linkgit:git-config[1]).
 
+NOTES
+-----
+
+Users often try to use the assume-unchanged and skip-worktree bits
+to tell Git to ignore changes to files that are tracked.  This does not
+work as expected, since Git may still check working tree files against
+the index when performing certain operations.  In general, Git does not
+provide a way to ignore changes to tracked files, so alternate solutions
+are recommended.
+
+For example, if the file you want to change is some sort of config file,
+the repository can include a sample config file that can then be copied
+into the ignored name and modified.  The repository can even include a
+script to treat the sample file as a template, modifying and copying it
+automatically.
+
 SEE ALSO
 --------
 linkgit:git-config[1],