Fix history uncluttering when Bash version is >= 5.1 (#57)

Since Bash version 5.1, the behaviour of HISTCMD has been changed and
it breaks history uncluttering. This commit solves this problem by
checking the Bash major version and by using the appropriate command
to unclutter the history.

Author: montag451

bash-completion.el

@@ -1218,45 +1218,52 @@ completion in these cases."
           ;; interfere with bash-completion-send detecting the end
           ;; of a command. It disables prompt to avoid interference
           ;; from commands run by prompts.
-          (comint-send-string
-           process
-           (concat
-            "set +o emacs;"
-            "set +o vi;"
-            "if [[ -z \"$__emacs_complete_ps1\" ]]; then"
-            "  __emacs_complete_ps1=\"$PS1\";"
-            "  __emacs_complete_pc=\"$PROMPT_COMMAND\";"
-            "fi;"
-            "PS1='' PROMPT_COMMAND='';"
-            "history &>/dev/null -d $((HISTCMD - 1)) || true\n"))
-
-          ;; The following is a bootstrap command for
-          ;; bash-completion-send itself.
-          (bash-completion-send
-           (concat
-            "function __emacs_complete_pre_command {"
-            "  if [[ -z \"$__emacs_complete_ps1\" ]]; then"
-            "    __emacs_complete_ps1=\"$PS1\";"
-            "    __emacs_complete_pc=\"$PROMPT_COMMAND\";"
-            "  fi;"
-            "  PROMPT_COMMAND=__emacs_complete_prompt;"
-            "  history &>/dev/null -d $((HISTCMD - 1)) || true;"
-            "} &&"
-            "function __emacs_complete_prompt {"
-            "  PS1=" bash-completion--ps1 ";"
-            "  PROMPT_COMMAND=__emacs_complete_recover_prompt;"
-            "} &&"
-            "function __emacs_complete_recover_prompt {"
-            "  local r=$?;"
-            "  PS1=\"${__emacs_complete_ps1}\";"
-            "  PROMPT_COMMAND=\"${__emacs_complete_pc}\";"
-            "  unset __emacs_complete_ps1 __emacs_complete_pc;"
-            "  if [[ -n \"$PROMPT_COMMAND\" ]]; then"
-            "    (exit $r); eval \"$PROMPT_COMMAND\";"
-            "  fi;"
-            "} &&"
-            "__emacs_complete_pre_command")
-           process)
+          (let* ((history-unclutter-cmd
+                  (concat
+                   "if [[ ${BASH_VERSINFO[0]} -eq 5 && ${BASH_VERSINFO[1]} -ge 1 || ${BASH_VERSINFO[0]} -gt 5 ]]; then"
+                   "  history -d $HISTCMD &>/dev/null || true;"
+                   "else"
+                   "  history -d $((HISTCMD - 1)) &>/dev/null || true;"
+                   "fi")))
+            (comint-send-string
+             process
+             (concat
+              "set +o emacs;"
+              "set +o vi;"
+              "if [[ -z \"$__emacs_complete_ps1\" ]]; then"
+              "  __emacs_complete_ps1=\"$PS1\";"
+              "  __emacs_complete_pc=\"$PROMPT_COMMAND\";"
+              "fi;"
+              "PS1='' PROMPT_COMMAND='';"
+              history-unclutter-cmd "\n"))
+
+            ;; The following is a bootstrap command for
+            ;; bash-completion-send itself.
+            (bash-completion-send
+             (concat
+              "function __emacs_complete_pre_command {"
+              "  if [[ -z \"$__emacs_complete_ps1\" ]]; then"
+              "    __emacs_complete_ps1=\"$PS1\";"
+              "    __emacs_complete_pc=\"$PROMPT_COMMAND\";"
+              "  fi;"
+              "  PROMPT_COMMAND=__emacs_complete_prompt;"
+              "  " history-unclutter-cmd ";"
+              "} &&"
+              "function __emacs_complete_prompt {"
+              "  PS1=" bash-completion--ps1 ";"
+              "  PROMPT_COMMAND=__emacs_complete_recover_prompt;"
+              "} &&"
+              "function __emacs_complete_recover_prompt {"
+              "  local r=$?;"
+              "  PS1=\"${__emacs_complete_ps1}\";"
+              "  PROMPT_COMMAND=\"${__emacs_complete_pc}\";"
+              "  unset __emacs_complete_ps1 __emacs_complete_pc;"
+              "  if [[ -n \"$PROMPT_COMMAND\" ]]; then"
+              "    (exit $r); eval \"$PROMPT_COMMAND\";"
+              "  fi;"
+              "} &&"
+              "__emacs_complete_pre_command")
+             process))
           (bash-completion--setup-bash-common process))
         process))))