Bug#785678: blends-dev: Do not drop virtual packages in alternatives

[Felipe Sateler <fsateler@debian.org>]

Package: blends-dev
Version: 0.6.92.2
Severity: wishlist

I use blends-dev to create local metapackages. I sometimes use the
common real-package | virtual-package pattern to specify a default but
allow alternatives. However, blends-dev removes the virtual-package
alternatives since they do not exist. It would be great if one could
pass an option or something to allow nonexistent packages in Depends
lines.

-- System Information:
Debian Release: stretch/sid
  APT prefers unstable
  APT policy: (500, 'unstable'), (1, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 4.0.0-1-amd64 (SMP w/4 CPU cores)
Locale: LANG=en_GB.UTF-8, LC_CTYPE=en_GB.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)

Versions of packages blends-dev depends on:
ii  build-essential  11.7
ii  debconf          1.5.56
ii  debhelper        9.20150507
ii  make             4.0-8.1

blends-dev recommends no packages.

Versions of packages blends-dev suggests:
pn  blends-doc  <none>

-- no debconf information