users/17955: new "disown" style for MIME handlers.

Makes handlers put into the background run without job control.

ChangeLog

@@ -1,5 +1,9 @@
 2013-08-29  Peter Stephenson  <p.stephenson@samsung.com>
 
+	* users/17955: Doc/Zsh/contrib.yo,
+	Functions/MIME/zsh-mime-handler: "disown" style makes MIME
+	handlers put into background run without job control.
+
 	* based on 31641, 31642: Completion/Unix/Command/_make: support
 	a couple of different variants of make.
 

Doc/Zsh/contrib.yo

@@ -2861,6 +2861,14 @@ question is run using the tt(eval) builtin instead of by starting a new
 tt(sh) process.  This is more efficient, but may not work in the occasional
 cases where the mailcap handler uses strict POSIX syntax.
 )
+kindex(disown, MIME style)
+item(tt(disown))(
+If this boolean style is true, mailcap handlers started in the
+background will be disowned, i.e. not subject to job control within
+the parent shell.  Such handlers nearly always produce their own
+windows, so the only likely harmful side effect of setting the style is
+that it becomes harder to kill jobs from within the shell.
+)
 kindex(execute-as-is, MIME style)
 item(tt(execute-as-is))(
 This style gives a list of patterns to be matched against files

Functions/MIME/zsh-mime-handler

@@ -74,7 +74,7 @@ if [[ $suffix != *.* ]]; then
 fi
 suffix=${suffix#*.}
 
-local handler flags no_sh no_bg arg
+local handler flags no_sh no_bg arg bg_flag="&"
 integer i
 local -a exec_asis hand_nonex
 
@@ -89,6 +89,9 @@ zsh-mime-contexts -a $suffix execute-as-is exec_asis || exec_asis=('*(*)' '*(/)'
 zsh-mime-contexts -a $suffix handle-nonexistent hand_nonex ||
   hand_nonex=('[[:alpha:]]#:/*')
 
+# Set to true if the job should be disowned.
+zsh-mime-contexts -t $suffix disown && bg_flag="&!"
+
 local pattern
 local -a files
 
@@ -309,8 +312,8 @@ else
   # Otherwise it's equivalent to removing the eval and all the quotes,
   # including the (q) flags.
   if [[ -n $stdin ]]; then
-    eval cat ${(q)argv} "|" ${(q)execargs} "&"
+    eval cat ${(q)argv} "|" ${(q)execargs} $bg_flag
   else
-    eval ${(q)execargs} "&"
+    eval ${(q)execargs} $bg_flag
   fi
 fi