buildrpm: complain when hg command isn't available

Before it complained "You are not inside a Mercurial repository!" which wasn't true.

contrib/buildrpm

@@ -1,65 +1,72
 #!/bin/sh
 #
 # Build a Mercurial RPM in place.
 # Known to work on:
 # - Fedora 9
+# - Fedora 10
 #
 # Bryan O'Sullivan <[e-mail]>
 
+if hg --version > /dev/null 2>&1; then :
+else
+    echo 'hg command not available!' 1>&2
+    exit 1
+fi
+
 root="`hg root 2>/dev/null`"
 specfile=contrib/mercurial.spec
 
 if [ -z "$root" ]; then
     echo 'You are not inside a Mercurial repository!' 1>&2
     exit 1
 fi
 
 rpmdir=/tmp/"`basename $root | sed 's/ /_/'`"-rpm # FIXME: Insecure /tmp handling
 
 cd "$root"
 rm -rf $rpmdir
 mkdir -p $rpmdir/RPMS
 hg clone "$root" $rpmdir/BUILD
 
 if [ ! -f $specfile ]; then
     echo "Cannot find $specfile!" 1>&2
     exit 1
 fi
 
 tmpspec=/tmp/`basename "$specfile"`.$$ # FIXME: Insecure /tmp handling
 # Use the most recent tag as the version.
 version=`hg tags | perl -e 'while(<STDIN>){if(/^(\d\S+)/){print$1;exit}}'`
 # Compute the release number as the difference in revision numbers
 # between the tip and the most recent tag.
 release=`hg tags | perl -e 'while(<STDIN>){($tag,$id)=/^(\S+)\s+(\d+)/;if($tag eq "tip"){$tip = $id}elsif($tag=~/^\d/){print $tip-$id+1;exit}}'`
 tip=`hg -q tip`
 
 # Beat up the spec file
 sed -e 's,^Source:.*,Source: /dev/null,' \
     -e "s,^Version:.*,Version: $version," \
     -e "s,^Release:.*,Release: $release," \
     -e "s,^%prep.*,Changeset: $tip\n\0," \
     -e 's,^%setup.*,,' \
     $specfile > $tmpspec
 
 cat <<EOF >> $tmpspec
 %changelog
 * `date +'%a %b %d %Y'` `hg showconfig ui.username` $version-$release
 - Automatically built via $0
 
 EOF
 hg log \
      --template '* {date|rfc822date} {author}\n- {desc|firstline}\n\n' \
      .hgtags \
   | sed -e 's/^\(\* [MTWFS][a-z][a-z]\), \([0-3][0-9]\) \([A-Z][a-z][a-z]\) /\1 \3 \2 /' \
         -e '/^\* [MTWFS][a-z][a-z] /{s/ [012][0-9]:[0-9][0-9]:[0-9][0-9] [+-][0-9]\{4\}//}' \
    >> $tmpspec
 
 rpmbuild --define "_topdir $rpmdir" -bb $tmpspec
 if [ $? = 0 ]; then
     rm -rf $tmpspec $rpmdir/BUILD
     mv $rpmdir/RPMS/*/* $rpmdir && rm -r $rpmdir/RPMS
     echo
     echo "Packages are in $rpmdir:"
     ls -l $rpmdir/*.rpm
 fi