vim-patch:8.0.0151,3,4 #7389

vim-patch:8.0.0151
Problem:    To pass buffer content to system() and systemlist() one has to
            first create a string or list.
Solution:   Allow passing a buffer number. (LemonBoy,
            closes vim/vim#1240)
12c4492dd3

vim-patch:8.0.0153
Problem:    system() test fails on MS-Windows.
Solution:   Deal when extra space and CR.
9d9c356517

vim-patch:8.0.0154
Problem:    system() test fails on OS/X.
Solution:   Deal with leading spaces.
31f19ce0a0

runtime/doc/eval.txt

@@ -7645,6 +7645,9 @@ system({cmd} [, {input}])				*system()* *E677*
 		|writefile()| does with {binary} set to "b" (i.e. with
 		a newline between each list item, and newlines inside list
 		items converted to NULs).
+		When {input} is given and is a valid buffer id, the content of
+		the buffer is written to the file line by line, each line
+		terminated by a NL (and NUL where the text has NL).
 								*E5677*
 		Note: system() cannot write to or read from backgrounded ("&")
 		shell commands, e.g.: >