Drop the requirement for having python on the server when using the ssh kitten

kittens/ssh/main.py

@@ -7,7 +7,6 @@ import sys
 
 SHELL_SCRIPT = '''\
 #!/bin/sh
-
 tmp=$(mktemp /tmp/terminfo.XXXXXX)
 cat >$tmp << 'TERMEOF'
 TERMINFO
@@ -17,47 +16,16 @@ tic_out=$(tic -x -o ~/.terminfo $tmp 2>&1)
 rc=$?
 rm $tmp
 if [ "$rc" != "0" ]; then echo "$tic_out"; exit 1; fi
-if [ -z "$USER" ]; then USER=$(whoami); fi
-search_for_python() {
-    # We have to search for python as Ubuntu, in its infinite wisdom decided
-    # to release 18.04 with no python symlink, making it impossible to run polyglot
-    # python scripts.
+if [ -z "$USER" ]; then export USER=$(whoami); fi
 
-    # We cannot use command -v as it is not implemented in the posh shell shipped with
-    # Ubuntu/Debian. Similarly, there is no guarantee that which is installed.
-    # Shell scripting is a horrible joke, thank heavens for python.
-    local IFS=:
-    if [ $ZSH_VERSION ]; then
-        # zsh does not split by default
-        setopt sh_word_split
-    fi
-    local candidate_path
-    local candidate_python
-    local pythons=python3:python2
-    # disable pathname expansion (globbing)
-    set -f
-    for candidate_path in $PATH
-    do
-        if [ ! -z $candidate_path ]
-        then
-            for candidate_python in $pythons
-            do
-                if [ ! -z "$candidate_path" ]
-                then
-                    if [ -x "$candidate_path/$candidate_python" ]
-                    then
-                        printf "$candidate_path/$candidate_python"
-                        return
-                    fi
-                fi
-            done
-        fi
-    done
-    set +f
-    printf "python"
-}
-PYTHON=$(search_for_python)
-exec $PYTHON -c "import os, pwd; shell = pwd.getpwuid(os.geteuid()).pw_shell or 'sh'; os.execlp(shell, '-' + os.path.basename(shell))"
+
+# We need to pass the first argument to the executed program with a leading -
+# to make sure the shell executes as a login shell. Note that not all shells
+# support exec -a
+shell_name=$(basename $0)
+exec -a "-$shell_name" "$0"
+# exec does not support -a
+exec "$0" --login
 '''