fixup! Support the use of additional APT repositories

README.md

@@ -97,7 +97,9 @@ Optional and empty by default.
 
 #### `extra-repos`
 Extra APT repositories to configure as sources in the build environment.
-Entries must be given in the “one-line-style format”, see
+
+Entries can be given in either format supported by APT: one-line style or
+deb822 style, see
 [`man sources.list`](https://manpages.debian.org/sources.list.5).
 
 Optional and empty by default.

scripts/install_build_deps

@@ -24,7 +24,12 @@ fi
 # essential packages. It is reasonably safe to blindly assume it is installed.
 printf "man-db man-db/auto-update boolean false\n" | debconf-set-selections
 
-printf "%s\n" "$INPUT_EXTRA_REPOS" >/etc/apt/sources.list.d/build-deb-action.list
+if printf "%s\n" "$INPUT_EXTRA_REPOS" | grep -q '^deb'; then
+	extra_repos_ext=.list
+else
+	extra_repos_ext=.sources
+fi
+printf "%s\n" "$INPUT_EXTRA_REPOS" >"/etc/apt/sources.list.d/build-deb-action${extra_repos_ext}"
 
 apt-get update