Handle multiple arguments in $PAGER

$PAGER may contain arguments, and should thus be word-split before 
invocation.

share/functions/__fish_paginate.fish

@@ -2,7 +2,7 @@ function __fish_paginate -d "Paginate the current command using the users defaul
 
     set -l cmd less
     if set -q PAGER
-        set cmd $PAGER
+        echo $PAGER | read -at cmd
     end
 
     if test -z (commandline -j | string join '')

share/functions/__fish_print_help.fish

@@ -110,7 +110,7 @@ function __fish_print_help --description "Print help message for the specified f
     begin
         set -l pager less
         set -q PAGER
-        and set pager $PAGER
+        and echo $PAGER | read -at pager
         not isatty stdout
         and set pager cat # cannot use a builtin here
         # similar to man, but add -F to quit paging when the help output is brief (#6227)

share/functions/history.fish

@@ -86,7 +86,7 @@ function history --description "display or manipulate interactive command histor
             if isatty stdout
                 set -l pager less
                 set -q PAGER
-                and set pager $PAGER
+                and echo $PAGER | read -at pager
 
                 # If the user hasn't preconfigured less with the $LESS environment variable,
                 # we do so to have it behave like cat if output fits on one screen. Prevent the