[PATCH] git-version-gen: Fix for tags containing '-'

[Markus Armbruster]

Really old versions of git-describe (before v1.5.0, Feb 2007) don't
have the number of commits in their long format output, i.e. where
modern 'git describe --abbrev=4 --match="v*"' prints
"v0.1-1494-g124b9", they print "v0.1-1494-g124b9".  git-version-gen
recognizes both patterns, and normalizes the old format to the new
one.

Unfortunately, this normalization code gets confused when the tag
contains '-'.  Reproducer:

    $ git-tag -m test v0.2-rc1
    $ build-aux/git-version-gen .tarball-version; echo
    build-aux/git-version-gen: WARNING: git rev-list failed
    UNKNOWN

We take exact tag "v0.2-rc1" for the old format, extract the presumed
tag "v0.2" from it, then run "git rev-list v0.2..HEAD" to count
commits since tha tag.  Fails, because tag "v0.2" does not exist.

We could perhaps drop support for versions from more than a decade
ago.  But tightening the pattern match is easy enough, so do that.
Still breaks when you use version tags ending in something matching
-g????, but you arguably get what you deserve then.

Signed-off-by: Markus Armbruster <address@hidden>
---
 build-aux/git-version-gen | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/build-aux/git-version-gen b/build-aux/git-version-gen
index 079849d..6c054b4 100755
--- a/build-aux/git-version-gen
+++ b/build-aux/git-version-gen
@@ -1,6 +1,6 @@
 #!/bin/sh
 # Print a version string.
-scriptversion=2017-01-09.19; # UTC
+scriptversion=2017-08-06.05; # UTC
 
 # Copyright (C) 2007-2017 Free Software Foundation, Inc.
 #
@@ -168,8 +168,8 @@ then
     #   Newer: v6.10-77-g0f8faeb
     #   Older: v6.10-g0f8faeb
     case $v in
-        *-*-*) : git describe is okay three part flavor ;;
-        *-*)
+        *-*-g????) : git describe is okay three part flavor ;;
+        *-g????)
             : git describe is older two part flavor
             # Recreate the number of commits and rewrite such that the
             # result is the same as if we were using the newer version
-- 
2.7.5