%e / %SBUILD_CHROOT_EXEC expansions fail

[Chris Halse Rogers]

If you run something like:

'''
sbuild -A -j 8 -d eoan --pre-build-commands 'cat foo | %SBUILD_CHROOT_EXEC sh -c "cat > bar"' zfs-linux_0.8.1-1ubuntu14.1.dsc
'''

it will fail with

'''
+------------------------------------------------------------------------------+
| Pre Build Commands |
+------------------------------------------------------------------------------+

cat foo | %SBUILD_CHROOT_EXEC sh -c "cat > bar"
------------------------------

/bin/sh: 1: %SBUILD_CHROOT_EXEC: not found
cat: foo: No such file or directory

E: Command 'cat foo | %SBUILD_CHROOT_EXEC sh -c "cat > bar"' failed to run.

Finished processing commands.
--------------------------------------------------------------------------------
E: Failed to execute pre-build-commands

'''

The sbuild manpage documents this command example as a way to pipe a file into the build chroot.

ProblemType: Bug
DistroRelease: Ubuntu 19.10
Package: sbuild 0.78.1-2ubuntu1
ProcVersionSignature: Ubuntu 5.2.21+bcachefs.git20191114.70e03772-1-generic 5.2.21
Uname: Linux 5.2.21+bcachefs.git20191114.70e03772-1-generic x86_64
NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair
ApportVersion: 2.20.11-0ubuntu8.2
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Mon Nov 18 16:12:55 2019
InstallationDate: Installed on 2019-08-29 (81 days ago)
InstallationMedia: Ubuntu 19.10 bcachefs (20190828)
PackageArchitecture: all
SourcePackage: sbuild
UpgradeStatus: No upgrade log present (probably fresh install)