Fall back if this is not a git checkout

diff --git a/src/Makefile.am b/src/Makefile.am
index 01b2a63d305ea8bcffa5841f374ccd51872f1032..bd710be0cbfdce6f2cc3b46ec97ec4f1d648c9b3 100644 (file)
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -488,7 +488,8 @@ revision.txt:
 
 stamp-revision:
        rm -f -- revision.tmp
-       git describe --tags --long --always > revision.tmp
+       (git --git-dir="$(top_srcdir)/.git/" describe --tags --long \
+               --always || echo exported) > revision.tmp
        diff revision.tmp revision.txt >/dev/null 2>&1 || \
        mv -f -- revision.tmp revision.txt