commit d3edc09c3f4fdce24d4f66c5a94302cae5d26980 (HEAD, refs/remotes/origin/master)
Author: Paul Eggert <eggert@cs.ucla.edu>
Date:   Wed Apr 13 18:19:04 2016 -0700

    Port ‘./autogen.sh git’ to non-clones
    
    Problem reported by Angelo Graziosi in:
    http://lists.gnu.org/archive/html/emacs-devel/2016-04/msg00341.html
    * autogen.sh (do_git): Default to false when the arg is ‘all’ but
    there is no ‘.git’.
    (git_common_dir, hooks): New vars.
    (git_config, tailored_hooks, sample_hooks): Use them.

diff --git a/autogen.sh b/autogen.sh
index 2e10a77..cd0accd 100755
--- a/autogen.sh
+++ b/autogen.sh
@@ -112,7 +112,8 @@ for arg; do
       --help)
 	exec echo "$0: usage: $0 [all|autoconf|git]";;
       all)
-	do_autoconf=true do_git=true;;
+	do_autoconf=true
+	test -e .git && do_git=true;;
       autoconf)
 	do_autoconf=true;;
       git)
@@ -260,7 +261,8 @@ git_config ()
 		echo 'Configuring local git repository...'
 		case $cp_options in
 		  --backup=*)
-		    cp $cp_options --force .git/config .git/config || exit;;
+		    config=$git_common_dir/config
+		    cp $cp_options --force -- "$config" "$config" || exit;;
 		esac
 	    fi
 	    echo "git config $name '$value'"
@@ -272,6 +274,13 @@ git_config ()
 
 ## Configure Git, if requested.
 
+# Get location of Git's common configuration directory.  For older Git
+# versions this is just '.git'.  Newer Git versions support worktrees.
+
+test -e .git && git_common_dir=`git rev-parse --git-common-dir 2>/dev/null` ||
+  git_common_dir=.git
+hooks=$git_common_dir/hooks
+
 # Check hashes when transferring objects among repositories.
 
 git_config transfer.fsckObjects true
@@ -296,12 +305,11 @@ tailored_hooks=
 sample_hooks=
 
 for hook in commit-msg pre-commit; do
-    cmp build-aux/git-hooks/$hook .git/hooks/$hook >/dev/null 2>&1 ||
+    cmp -- build-aux/git-hooks/$hook "$hooks/$hook" >/dev/null 2>&1 ||
 	tailored_hooks="$tailored_hooks $hook"
 done
 for hook in applypatch-msg pre-applypatch; do
-    src=.git/hooks/$hook.sample
-    cmp "$src" .git/hooks/$hook >/dev/null 2>&1 ||
+    cmp -- "$hooks/$hook.sample" "$hooks/$hook" >/dev/null 2>&1 ||
 	sample_hooks="$sample_hooks $hook"
 done
 
@@ -311,15 +319,15 @@ if test -n "$tailored_hooks$sample_hooks"; then
 
 	if test -n "$tailored_hooks"; then
 	    for hook in $tailored_hooks; do
-		dst=.git/hooks/$hook
-		cp $cp_options build-aux/git-hooks/$hook "$dst" || exit
-		chmod a-w "$dst" || exit
+		dst=$hooks/$hook
+		cp $cp_options -- build-aux/git-hooks/$hook "$dst" || exit
+		chmod -- a-w "$dst" || exit
 	    done
 	fi
 
 	if test -n "$sample_hooks"; then
 	    for hook in $sample_hooks; do
-		cp $cp_options .git/hooks/$hook.sample .git/hooks/$hook || exit
+		cp $cp_options -- "$hooks/$hook.sample" "$hooks/$hook" || exit
 		chmod a-w .git/hooks/$hook || exit
 	    done
 	fi

commit 1aebe99145e9ef612cdb272800904e3ba9297196
Author: Paul Eggert <eggert@cs.ucla.edu>
Date:   Wed Apr 13 11:12:15 2016 -0700

    Do not require that .git be a directory
    
    Problem reportyed by Phillip Lord.
    * admin/update_autogen, autogen.sh, build-aux/gitlog-to-emacslog:
    * configure.ac, make-dist:
    Do not require that .git be a directory, as 'git worktree' makes
    it a file and not a directory.

diff --git a/admin/update_autogen b/admin/update_autogen
index 199a3aa..1e8aae2 100755
--- a/admin/update_autogen
+++ b/admin/update_autogen
@@ -49,7 +49,7 @@ cd ../
 
 if [ -d .bzr ]; then
     vcs=bzr
-elif [ -d .git ]; then
+elif [ -e .git ]; then
     vcs=git
 else
     die "Cannot determine vcs"
diff --git a/autogen.sh b/autogen.sh
index 9042465..2e10a77 100755
--- a/autogen.sh
+++ b/autogen.sh
@@ -330,7 +330,7 @@ fi
 
 if test ! -f configure; then
     echo "You can now run '$0 autoconf'."
-elif test -d .git && test $git_was_ok = false && test $do_git = false; then
+elif test -e .git && test $git_was_ok = false && test $do_git = false; then
     echo "You can now run '$0 git'."
 elif test ! -f config.status ||
 	test -n "`find src/stamp-h.in -newer config.status`"; then
diff --git a/build-aux/gitlog-to-emacslog b/build-aux/gitlog-to-emacslog
index 5c187f5..6b9cfc1 100755
--- a/build-aux/gitlog-to-emacslog
+++ b/build-aux/gitlog-to-emacslog
@@ -68,7 +68,7 @@ if [ -f "$output" ]; then
 fi
 
 # If this is not a Git repository, just generate an empty ChangeLog.
-test -d .git || {
+test -e .git || {
   >"$output"
   exit
 }
diff --git a/configure.ac b/configure.ac
index 790ff84..8f311cf 100644
--- a/configure.ac
+++ b/configure.ac
@@ -874,11 +874,11 @@ AC_ARG_ENABLE([gcc-warnings],
    gl_gcc_warnings=$enableval],
   [# By default, use 'warn-only' if it looks like the invoker of 'configure'
    # is a developer as opposed to a builder.  This is most likely true
-   # if GCC is recent enough and there is a .git subdirectory;
+   # if GCC is recent enough and there is a .git directory or file;
    # however, if there is also a .tarball-version file it is probably
    # just a release imported into Git for patch management.
    gl_gcc_warnings=no
-   test -d "$srcdir"/.git && test ! -f "$srcdir"/.tarball-version &&
+   test -e "$srcdir"/.git && test ! -f "$srcdir"/.tarball-version &&
      gl_GCC_VERSION_IFELSE([5], [3], [gl_gcc_warnings=warn-only])]
 )
 
diff --git a/make-dist b/make-dist
index 1cd1a50..c0b0a04 100755
--- a/make-dist
+++ b/make-dist
@@ -284,7 +284,7 @@ echo "Creating top directory: '${tempdir}'"
 mkdir ${tempdir}
 
 if [ "$changelog" = yes ]; then
-  if test -d .git; then
+  if test -e .git; then
     echo "Making top-level ChangeLog"
     make ChangeLog CHANGELOG=${tempdir}/ChangeLog || \
       { x=$?; echo "make ChangeLog FAILED (try --no-changelog?)" >&2; exit $x; }