bug#20234: 25.0.50; `multi-isearch-end' should reset `multi-isearch-buffer-list' to nil

[Drew Adams]

This is in some sense a companion bug report to #20232.

The `multi-isearch' commands set `multi-isearch-buffer-list' to the set
of buffers being searched.  But this variable should be reset by
`multi-isearch-end', so that other functions can use
`multi-isearch-buffer-list' to test whether normal Isearch or
`multi-search' is in progress.

For example, I have code that does something similar to what `M-s h r'
does, but it works also across the multiple buffers searched by
`multi-isearch-buffers*'.  Currently I have to advise
`multi-isearch-end' so that it resets `multi-isearch-buffer-list' to
nil.  It should do this anyway, I think.


In GNU Emacs 25.0.50.1 (i686-pc-mingw32)
 of 2014-10-20 on LEG570
Bzr revision: 118168 rgm@gnu.org-20141020195941-icp42t8ttcnud09g
Windowing system distributor `Microsoft Corp.', version 6.1.7601
Configured using:
 `configure --enable-checking=yes,glyphs CPPFLAGS=-DGLYPH_DEBUG=1'