contrib/plan9/9diff

packaging: remove version info from Breaks+Replaces in Debian package

The versioned Breaks: and Replaces: cause problem when trying to install
our package over the one in Debian.

  $ sudo apt install ./packages/debian-buster/mercurial_5.2~rc0+15-buster-a2ff3aff81d2_amd64.deb
  Reading package lists... Done
  Building dependency tree
  Reading state information... Done
  Note, selecting 'mercurial' instead of './packages/debian-buster/mercurial_5.2~rc0+15-buster-a2ff3aff81d2_amd64.deb'
  Some packages could not be installed. This may mean that you have
  requested an impossible situation or if you are using the unstable
  distribution that some required packages have not yet been created
  or been moved out of Incoming.
  The following information may help to resolve the situation:

  The following packages have unmet dependencies:
   mercurial : Breaks: mercurial-common (< 5.2~rc0+15-buster-a2ff3aff81d2) but 5.2~rc0-1 is to be installed
  E: Unable to correct problems, you have held broken packages.

Removing version information resolves the situation.

#!/bin/rc
# 9diff - Mercurial extdiff wrapper for diff(1)

rfork e

fn getfiles {
	cd $1 &&
	for(f in `{du -as | awk '{print $2}'})
		test -f $f && echo `{cleanname $f}
}

fn usage {
	echo >[1=2] usage: 9diff [diff options] parent child root
	exit usage
}

opts=()
while(~ $1 -*){
	opts=($opts $1)
	shift
}
if(! ~ $#* 3)
	usage

# extdiff will set the parent and child to a single file if there is
# only one change. If there are multiple changes, directories will be
# set. diff(1) does not cope particularly with directories; instead we
# do the recursion ourselves and diff each file individually.
if(test -f $1)
	diff $opts $1 $2
if not{
	# extdiff will create a snapshot of the working copy to prevent
	# conflicts during the diff. We circumvent this behavior by
	# diffing against the repository root to produce plumbable
	# output. This is antisocial.
	for(f in `{sort -u <{getfiles $1} <{getfiles $2}}){
		file1=$1/$f; test -f $file1 || file1=/dev/null
		file2=$3/$f; test -f $file2 || file2=/dev/null
		diff $opts $file1 $file2
	}
}
exit ''