setup.c: detect $GIT_COMMON_DIR in is_git_directory()

diff --git a/Documentation/gitignore.txt b/Documentation/gitignore.txt
index 82b7e0b1512702b61a1cd28e024583a3488991d8..09e82c31bd320a162689a7f2d919de439d05375a 100644 (file)
--- a/Documentation/gitignore.txt
+++ b/Documentation/gitignore.txt
@@ -7,7 +7,7 @@ gitignore - Specifies intentionally untracked files to ignore
 
 SYNOPSIS
 --------
-$GIT_DIR/info/exclude, .gitignore
+$HOME/.config/git/ignore, $GIT_DIR/info/exclude, .gitignore
 
 DESCRIPTION
 -----------
@@ -82,8 +82,10 @@ PATTERN FORMAT
 
  - An optional prefix "`!`" which negates the pattern; any
    matching file excluded by a previous pattern will become
-   included again.  If a negated pattern matches, this will
-   override lower precedence patterns sources.
+   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.
    Put a backslash ("`\`") in front of the first "`!`" for patterns
    that begin with a literal "`!`", for example, "`\!important!.txt`".
 
@@ -185,6 +187,19 @@ Another example:
 The second .gitignore prevents Git from ignoring
 `arch/foo/kernel/vmlinux.lds.S`.
 
+Example to exclude everything except a specific directory `foo/bar`
+(note the `/*` - without the slash, the wildcard would also exclude
+everything within `foo/bar`):
+
+--------------------------------------------------------------
+    $ cat .gitignore
+    # exclude everything except directory foo/bar
+    /*
+    !/foo
+    /foo/*
+    !/foo/bar
+--------------------------------------------------------------
+
 SEE ALSO
 --------
 linkgit:git-rm[1],