Switch default debootstrap tool to mmdebstrap

mmdebstrap is the modern, fast tool. grml-small comes with mmdebstrap
but not debootstrap, so it's really necessary there.

Closes: #290

.github/workflows/test-build.yml

@@ -60,7 +60,7 @@ jobs:
         - stretch
 
         debootstrap:
-        - ''
+        - debootstrap
         - mmdebstrap
 
         exclude:

config

@@ -101,8 +101,8 @@
 
 # Name of debootstrap executable.
 # Supported values: 'debootstrap', 'cdebootstrap', 'mmdebstrap'
-# Default: 'debootstrap'
-# DEBOOTSTRAP='debootstrap'
+# Default: 'mmdebstrap'
+# DEBOOTSTRAP='mmdebstrap'
 
 # Pass extra options to debootstrap.
 # Default: no default.

debian/control

@@ -25,7 +25,7 @@ Architecture: all
 Depends:
  bash (>= 4.3-11+deb8u2),
  debian-archive-keyring,
- debootstrap (>= 1.0.65) | cdebootstrap (>= 0.3.16) | mmdebstrap,
+ mmdebstrap | debootstrap (>= 1.0.65) | cdebootstrap (>= 0.3.16),
  dosfstools,
  e2fsprogs,
  fdisk | util-linux (<< 2.29.2-3~),

grml-debootstrap

@@ -50,7 +50,7 @@ MNTPOINT="/mnt/debootstrap.$$"
 [ -n "$CONFFILES" ] || CONFFILES='/etc/debootstrap'
 [ -n "$DEBCONF" ] || DEBCONF='yes'
 [ -n "$DEBIAN_FRONTEND" ] || DEBIAN_FRONTEND='noninteractive'
-[ -n "$DEBOOTSTRAP" ] || DEBOOTSTRAP='debootstrap'
+[ -n "$DEBOOTSTRAP" ] || DEBOOTSTRAP='mmdebstrap'
 [ -n "$DEFAULT_LANGUAGE" ] || DEFAULT_LANGUAGE='en_US:en'
 [ -n "$DEFAULT_LOCALES" ] || DEFAULT_LOCALES='en_US.UTF-8'
 [ -n "$DISK_IDENTIFIER" ] || DISK_IDENTIFIER='26ada0c0-1165-4098-884d-aafd2220c2c6'