Revert "Assume unknown shells are bash-compatible"

This reverts commit 22618b1.
This reverts commit 45efe53.
This reverts commit 00e2131.
This reverts commit a4dc56f.

libexec/jenv-hooks

@@ -47,7 +47,7 @@ shopt -s nullglob
 for path in ${JENV_HOOK_PATH//:/$'\n'}; do
 
   case "$shell" in
-  bash | * )
+  bash )
     for script in $path/"$JENV_COMMAND"/*.bash; do
     echo $(realpath $script)
     done

libexec/jenv-init

@@ -22,11 +22,17 @@ done
 
 shell="$1"
 if [ -z "$shell" ]; then
-  shell="$(ps -p "$PPID" -o 'args=' 2>/dev/null || true)"
-  shell="${shell%% *}"
-  shell="${shell##-}"
-  shell="${shell:-$SHELL}"
-  shell="${shell##*/}"
+  if [-n "$BASH_VERSIONH"]; then
+      shell="bash"
+  elif [ -n "$ZSH_VERSION"]; then
+      shell="zsh"
+  elif [ -n "FISH_VERSION"]; then
+      shell="fish"
+  elif [ -n "KSH_VERSION"]; then
+      shell="ksh"
+  else
+      shell="unknown"
+  fi
 fi
 
 resolve_link() {
@@ -95,7 +101,7 @@ fish )
   echo "set -e JAVA_HOME"
   echo "set -e JDK_HOME"
   ;;
-bash | zsh | * )
+bash | zsh )
   echo 'export PATH="'${JENV_ROOT}'/shims:${PATH}"'
   echo "export JENV_SHELL=$shell"
   echo "export JENV_LOADED=1"
@@ -137,11 +143,11 @@ function jenv
 end
 EOS
   ;;
-bash | zsh | * )
+bash | zsh )
   IFS="|"
   cat <<EOS
 jenv() {
-  type typeset &> /dev/null && typeset command
+  typeset command
   command="\$1"
   if [ "\$#" -gt 0 ]; then
     shift