[aisleriot] build: Fix ChangeLog rule to work on a git worktree

[Christian Persch <chpe src gnome org>]

commit a2d1187bc052e599ef73ee640a28cbb2c4f23c2f
Author: Christian Persch <chpe src gnome org>
Date:   Mon Sep 9 21:54:18 2019 +0200

    build: Fix ChangeLog rule to work on a git worktree

 Makefile.am | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)
---
diff --git a/Makefile.am b/Makefile.am
index 4f2451b6..cfe84089 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -58,7 +58,7 @@ MAINTAINERCLEANFILES = \
 
 # Build ChangeLog from git log
 ChangeLog:
-       $(AM_V_GEN) if test -f $(top_srcdir)/.git/HEAD; then \
+       $(AM_V_GEN) if test -e $(top_srcdir)/.git; then \
                git log --stat --no-color --since=2008-06-21 > $@; \
        fi
 
@@ -67,4 +67,3 @@ dist: ChangeLog
 .PHONY: ChangeLog
 
 -include $(top_srcdir)/git.mk
-