Merge branch 'nd/exclusion-regression-fix'

Another try to add support to the ignore mechanism that lets you
say "this is excluded" and then later say "oh, no, this part (that
is a subset of the previous part) is not excluded".

* nd/exclusion-regression-fix:
  dir.c: don't exclude whole dir prematurely
  dir.c: support marking some patterns already matched
  dir.c: support tracing exclude
  dir.c: fix match_pathname()

Documentation/git-check-ignore.txt

@@ -114,6 +114,7 @@ SEE ALSO
 linkgit:gitignore[5]
 linkgit:gitconfig[5]
 linkgit:git-ls-files[1]
+GIT_TRACE_EXCLUDE in linkgit:git[1]
 
 GIT
 ---

Documentation/git.txt

@@ -1065,6 +1065,11 @@ of clones and fetches.
 	cloning of shallow repositories.
 	See 'GIT_TRACE' for available trace output options.
 
+'GIT_TRACE_EXCLUDE'::
+	Enables trace messages that can help debugging .gitignore
+	processing. See 'GIT_TRACE' for available trace output
+	options.
+
 'GIT_LITERAL_PATHSPECS'::
 	Setting this variable to `1` will cause Git to treat all
 	pathspecs literally, rather than as glob patterns. For example,

Documentation/gitignore.txt

@@ -82,12 +82,12 @@ PATTERN FORMAT
 
  - An optional prefix "`!`" which negates the pattern; any
    matching file excluded by a previous pattern will become
-   included again. It is not possible to re-include a file if a parent
-   directory of that file is excluded. Git doesn't list excluded
-   directories for performance reasons, so any patterns on contained
-   files have no effect, no matter where they are defined.
+   included again.
    Put a backslash ("`\`") in front of the first "`!`" for patterns
    that begin with a literal "`!`", for example, "`\!important!.txt`".
+   It is possible to re-include a file if a parent directory of that
+   file is excluded if certain conditions are met. See section NOTES
+   for detail.
 
  - If the pattern ends with a slash, it is removed for the
    purpose of the following description, but it would only find
@@ -141,6 +141,15 @@ not tracked by Git remain untracked.
 To stop tracking a file that is currently tracked, use
 'git rm --cached'.
 
+To re-include files or directories when their parent directory is
+excluded, the following conditions must be met:
+
+ - The rules to exclude a directory and re-include a subset back must
+   be in the same .gitignore file.
+
+ - The directory part in the re-include rules must be literal (i.e. no
+   wildcards)
+
 EXAMPLES
 --------