fix for %P in TIMEFORMAT; make updating variables that aren't subject to allexport smoother; fix spurious compiler warning about realloc; efficiency improvement for command timing; fix issue with read builtin and failure to set terminal attributes

doc/bash.1

@@ -2513,6 +2513,10 @@ A filename whose suffix matches one of the entries in
 is excluded from the list of matched filenames.
 A sample value is
 .Q .o:\*~ .
+Since tilde expansion takes place after
+.Q :
+in assignment statements,
+make sure to quote assignments appropriately to avoid it as appropriate.
 .TP
 .B FUNCNEST
 If set to a numeric value greater than 0, defines a maximum function