http://bugs.gentoo.org/355045

[PATCH] git-version-gen: skip "-dirty" check when appropriate

* build-aux/git-version-gen: Don't run any git commands
when the version comes from .tarball-version.  Prior to this,
we would run git update-index --refresh even from a just-unpacked
tarball directory, and that could affect a .git/ directory in a
parent of the build directory.  Reported by Mike Frysinger.

diff --git a/build-aux/git-version-gen b/build-aux/git-version-gen
index 68c7d64..686f703 100755
--- a/build-aux/git-version-gen
+++ b/build-aux/git-version-gen
@@ -124,13 +124,16 @@
     # Change the first '-' to a '.', so version-comparing tools work properly.
     # Remove the "g" in git describe's output string, to save a byte.
     v=`echo "$v" | sed 's/-/./;s/\(.*\)-g/\1-/'`;
+    v_from_git=1
 else
     v=UNKNOWN
+    v_from_git=
 fi
 
 v=`echo "$v" |sed 's/^v//'`
 
 # Don't declare a version "dirty" merely because a time stamp has changed.
+if test -n "$v_from_git"; then
 git update-index --refresh > /dev/null 2>&1
 
 dirty=`sh -c 'git diff-index --name-only HEAD' 2>/dev/null` || dirty=
@@ -142,6 +145,7 @@
 	  *) v="$v-dirty" ;;
 	esac ;;
 esac
+fi
 
 # Omit the trailing newline, so that m4_esyscmd can use the result directly.
 echo "$v" | tr -d "$nl"