Accomodate user insistance on HISTCONTROL

If the user still sets `$HISTCONTROL` incompatibly anyway (`ignorespace`), then gracefully fall back to a less-ideal but not-incorrect `$BASH_COMMAND`. Alsö, adopt a modification of @cornfeedhobo's suggestion that doesn't require Bash v5.

Author: gaelicWizard

README.md

@@ -97,8 +97,6 @@ This is disabled by default due to buggy situations related to to `functrace` an
 
 In order to be able to provide the last command text to the `preexec` hook, this script will remove `ignorespace` and/or will replace `ignoreboth` with `ignoredups` in your `HISTCONTROL` variable.  It will remember if `HISTCONTROL` has been modified and will remove the last command from the history "manually", after reading the last command from the history list.  This may cause issues when you have scripts that rely on the literal value of `HISTCONTROL` or manipulate history in their own ways.
 
-Unfortunately, this only works with Bash 5.0 and above.  In older version of Bash, `ignorespace` and `ignoreboth` will be just silently ignored.
-
 ## Tests
 You can run tests using [Bats](https://github.com/bats-core/bats-core).
 ```bash

bash-preexec.sh

@@ -65,7 +65,7 @@ __bp_require_not_readonly() {
   local var
   for var; do
     if ! ( unset "$var" 2> /dev/null ); then
-      echo "bash-preexec requires write access to ${var}" >&2
+      echo "${BASH_SOURCE##*/} requires write access to ${var}" >&2
       return 1
     fi
   done
@@ -91,7 +91,7 @@ __bp_adjust_histcontrol() {
         histcontrol="${histcontrol//ignoreboth}"
         histcontrol="ignoredups${histcontrol:+:}${histcontrol}"
     fi;
-    export HISTCONTROL="$histcontrol"
+    HISTCONTROL="$histcontrol"
 }
 
 # This variable describes whether we are currently in "interactive mode";
@@ -214,8 +214,7 @@ __bp_preexec_invoke_exec() {
         return
     fi
     if [[ -z "${__bp_preexec_interactive_mode:-}" ]]; then
-        # We're doing something related to displaying the prompt.  Let the
-        # prompt set the title instead of me.
+        # We're doing something related to displaying the prompt. 
         return
     else
         # If we're in a subshell, then the prompt won't be re-displayed to put
@@ -236,10 +235,12 @@ __bp_preexec_invoke_exec() {
     fi
 
     local this_command
-    this_command=$(
-        export LC_ALL=C
-        HISTTIMEFORMAT= builtin history 1 | sed '1 s/^ *[0-9][0-9]*[* ] //'
-    )
+    if [[ "$HISTCONTROL" == *ignore+(both|space)* ]]
+    then
+        this_command="${BASH_COMMAND:-}"
+    else
+        this_command="$( HISTTIMEFORMAT= builtin history 1 | sed '1 s/^ *[0-9][0-9]*[* ] //' )"
+    fi
 
     # Sanity check to make sure we have something to invoke our function with.
     if [[ -z "$this_command" ]]; then
@@ -249,13 +250,8 @@ __bp_preexec_invoke_exec() {
     # If we have remove "ignorespace" or "ignoreboth" from HISTCONTROL during
     # setup, we need to remove commands that start with a space from the
     # history ourselves.
-
-    # Unfortunately, we need bash 5.0 or above, as "history -d" does not
-    # support negative indices in earlier versions and HISTCMD seems to be
-    # unreliable.  At least in the unit tests HISTCMD is just set to 1, after
-    # any number of "history -s" calls.
-    if [[ "${BASH_VERSINFO:-0}" -ge 5 && -n "$__bp_ignorespace" && "$this_command" == " "* ]]; then
-      builtin history -d -1
+    if [[ -n "${__bp_ignorespace:-}" && "$this_command" == " "* ]]; then
+      history -d "$(HISTTIMEFORMAT= builtin history 1 | sed -r '1 s/^ *([0-9][0-9]*)[* ] .*$/\1/')"
     fi
 
     # Invoke every function defined in our function array.
@@ -265,7 +261,6 @@ __bp_preexec_invoke_exec() {
     for preexec_function in "${preexec_functions[@]:-}"; do
 
         # Only execute each function if it actually exists.
-        # Test existence of function with: declare -[fF]
         if type -t "$preexec_function" 1>/dev/null; then
             __bp_set_ret_value ${__bp_last_ret_value:-}
             # Quote our function invocation to prevent issues with IFS