Do not cripple version if last tag was not found

IOW, it's not guaranteed that once we are in git repo we can always see
the tag.  VERSION should be reliable, though.

utils/mkit/include/build.sh

     # meta-data is to *identify* the code, and provide safe path back
     # to tree; commit refs are already perfect for that.
     #
-    # FIXME:  The assumpton "if we are in git repo, we can read version
-    #         from tags" fails if we are in shallow clone made from
-    #         other than a tagged commit.
-    #
     # FIXME:  Using PRERELEASE for release IDs may not be compatible with
     #         release strategy implemented in release.sh
     #
         then    # the tree is "dirty", i.e. has been edited
             local dirty=dirty
         fi
-        version=${lasttag:1}
+        test -n "$lasttag" && version=${lasttag:1}
         local suffix=""
         case $prerl:$commit:$dirty in
             ::)        suffix=""                       ;;