Update bash-preexec.sh

- Avoids infinite recursion with things like export PROMPT_COMMAND="history -a; $PROMPT_COMMAND"
- Preserve trap DEBUG again: revert rcaloras#60

bash-preexec.sh

@@ -45,6 +45,9 @@ __bp_imported="defined"
 __bp_last_ret_value="$?"
 __bp_last_argument_prev_command="$_"
 
+__bp_inside_precmd=0
+__bp_inside_preexec=0
+
 # Remove ignorespace and or replace ignoreboth from HISTCONTROL
 # so we can accurately invoke preexec with a command from our
 # history even if it starts with a space.
@@ -83,6 +86,13 @@ __bp_interactive_mode() {
 # This function is installed as part of the PROMPT_COMMAND.
 # It will invoke any functions defined in the precmd_functions array.
 __bp_precmd_invoke_cmd() {
+    # Don't invoke precmds if we are inside an execution of an "original
+    # prompt command" by another precmd execution loop. This avoids infinite
+    # recursion.
+    if (( __bp_inside_precmd > 0 )); then
+      return
+    fi
+    local __bp_inside_precmd=1
 
     # Save the returned value from our last command
     __bp_last_ret_value="$?"
@@ -137,6 +147,12 @@ __bp_preexec_invoke_exec() {
     # https://stackoverflow.com/questions/40944532/bash-preserve-in-a-debug-trap#40944702
     __bp_last_argument_prev_command="$1"
 
+    # Don't invoke preexecs if we are inside of another preexec.
+    if (( __bp_inside_preexec > 0 )); then
+      return;
+    fi
+    local __bp_inside_preexec=1
+
     # Checks if the file descriptor is not standard out (i.e. '1')
     # __bp_delay_install checks if we're in test. Needed for bats to run.
     # Prevents preexec from being invoked for functions in PS1
@@ -277,15 +293,12 @@ __bp_install_after_session_init() {
       precmd_functions+=(__bp_original_prompt_command)
     fi
 
-    # Save anything already defined in our trap
-    __bp_trap_string="$(trap -p DEBUG)"
-
     # Installation is finalized in PROMPT_COMMAND, which allows us to override the DEBUG
     # trap. __bp_install sets PROMPT_COMMAND to its final value, so these are only
     # invoked once.
     # It's necessary to clear any existing DEBUG trap in order to set it from the install function.
     # Using \n as it's the most universal delimiter of bash commands
-    PROMPT_COMMAND=$'\ntrap DEBUG\n__bp_install\n'
+    PROMPT_COMMAND=$'\n__bp_trap_string="$(trap -p DEBUG)"\n trap DEBUG\n __bp_install\n'
 }
 
 # Run our install so long as we're not delaying it.