fix(_comp_load): work around custom IFS, word splitting, and failglob

Author: akinomyoga

bash_completion

@@ -3327,7 +3327,7 @@ _comp_load()
     if [[ $rawcmd == \\* ]]; then
         origcmd=${rawcmd:1}
         # If we already have a completion for the "real" command, use it
-        $(complete -p -- "$origcmd" 2>/dev/null || echo false) "$rawcmd" && return 0
+        eval -- "$(complete -p -- "$origcmd" 2>/dev/null || echo false) \"\$rawcmd\"" && return 0
     fi
 
     local cmdname=${origcmd##*/}
@@ -3404,18 +3404,18 @@ _comp_load()
                         # $rawcmd contains the raw shell word before processing
                         # backslash
                         [[ $rawcmd != "$cmd" ]] &&
-                            eval "$compspec \"\$rawcmd\""
+                            eval -- "$compspec \"\$rawcmd\""
                         # If invoked without path, that one should be set, too
                         # ...but let's not overwrite an existing one, if any
                         [[ $origcmd != "$cmd" && $origcmd != "$rawcmd" ]] &&
                             ! complete -p -- "$origcmd" &>/dev/null &&
-                            eval "$compspec \"\$origcmd\""
+                            eval -- "$compspec \"\$origcmd\""
                         return 0
                     fi
                     # If not, see if we got one for $cmdname
                     if [[ $cmdname != "$cmd" ]] && compspec=$(complete -p -- "$cmdname" 2>/dev/null); then
                         # Use that for $cmd too, if we have a full path to it
-                        [[ $cmd == /* ]] && eval "$compspec \"\$cmd\""
+                        [[ $cmd == /* ]] && eval -- "$compspec \"\$cmd\""
                         return 0
                     fi
                     # Nothing expected was set, continue lookup