fix(ri): properly split methods

The current implementation of `_comp_cmd_ri__methods` generates
methods separated by newlines as a single element of COMPREPLY, which
is suspicous.  This code existed since the first implementation of the
"ri" completion in commit 309cf93.  In this patch, we try to split
the result with newlines.

completions/ri

@@ -14,19 +14,19 @@ _comp_cmd_ri__methods()
             regex=Class
         fi
 
-        COMPREPLY+=(
+        _comp_split -la COMPREPLY \
             "$(ri ${classes[@]+"${classes[@]}"} 2>/dev/null | ruby -ane \
                 'if /^'"$regex"' methods:/.../^------------------|^$/ and \
             /^ / then print $_.split(/, |,$/).grep(/^[^\[]*$/).join("\n"); \
-            end' 2>/dev/null | sort -u)")
+            end' 2>/dev/null | sort -u)"
     else
         # older versions of ri didn't distinguish between class/module and
         # instance methods
-        COMPREPLY+=(
+        _comp_split -la COMPREPLY \
             "$(ruby -W0 "$ri_path" ${classes[@]+"${classes[@]}"} 2>/dev/null | ruby -ane \
                 'if /^-/.../^-/ and ! /^-/ and ! /^ +(class|module): / then \
             print $_.split(/, |,$| +/).grep(/^[^\[]*$/).join("\n"); \
-            end' | sort -u)")
+            end' | sort -u)"
     fi
     ((${#COMPREPLY[@]})) &&
         _comp_compgen -c "$method" -- "$prefix" -W '"${COMPREPLY[@]}"'