rm: expand the index only when necessary

Originally, rm a pathspec that is out-of-cone in a sparse-index
environment, Git dies with "pathspec '<x>' did not match any files",
mainly because it does not expand the index so nothing is matched.

Remove the `ensure_full_index()` method so `git-rm` does not always
expand the index when the expansion is unnecessary, i.e. when
<pathspec> does not have any possibilities to match anything outside
of sparse-checkout definition.

Expand the index when the <pathspec> needs an expanded index, i.e. the
<pathspec> contains wildcard that may need a full-index or the
<pathspec> is simply outside of sparse-checkout definition.

Signed-off-by: Shaoxuan Yuan <[email protected]>

Author: ffyuanda

builtin/rm.c

@@ -296,8 +296,9 @@ int cmd_rm(int argc, const char **argv, const char *prefix)
 
 	seen = xcalloc(pathspec.nr, 1);
 
-	/* TODO: audit for interaction with sparse-index. */
-	ensure_full_index(&the_index);
+	if (pathspec_needs_expanded_index(&the_index, &pathspec))
+		ensure_full_index(&the_index);
+
 	for (i = 0; i < active_nr; i++) {
 		const struct cache_entry *ce = active_cache[i];