would not be properly closed under the path reference relation.

  option `--keep-failed' to override this behaviour.

    ("srcs", [Relative("foo/bar.c"), Relative("foo/baz.h")])

  The result is an environment variable that contains the path names of the
  inputs separated by spaces (so this is not safe for values containing
  spaces).

  when PATH is not set.  We don't want this, so fill it in with
  some dummy value. 

* Put `@' in front of echo's in the Makefile.

  builder using the `args' binding:

  ("args", ["bla", True, IncludeFix("aterm/aterm.fix")])

  Note that packages can also be declared as inputs by specifying them
  in the argument list.

  builder.  Note that this unfortunately causes all Fix-computed
  hashes to change.

  store, and print its hash.

  when we delete entries from a directory while we are reading it.
  So read the directory into memory, then delete its contents.

  NAME'.  E.g., on the losser Subversion server, I do `nix-switch --name 
  svn $(fix ...)' to atomically upgrade the server (the SVN server 
  uses the Apache and Subversion installations in /nix/var/nix/links/svn).

* Use nix-hash (not md5sum) in fetchurl.sh.

  process is already holding a lock on a path, it may acquire the lock
  again without blocking or failing).  (This might be dangerous, not
  sure).  Necessary for fast builds to work.

  a regular file.  I.e., `nix-hash --flat' is equivalent to the
  coreutils `md5sum' command (which doesn't exist on all systems).

* Allow booleans in package environment bindings (True maps to "1",
  False maps to "").

  the same time.

  normalise to Nix expression.