zsh: complete unquoted paths with spaces correctly

The following is the description of -Q flag of zsh compadd [1]:

    This flag instructs the completion code not to quote any
    metacharacters in the words when inserting them into the command
    line.

Let's say there is a file named 'foo bar.txt' in repository, but it's
not yet added to the repository. Then the following command triggers a
completion:

    git add fo<Tab>
    git add 'fo<Tab>
    git add "fo<Tab>

The completion results in bash:

    git add foo\ bar.txt
    git add 'foo bar.txt'
    git add "foo bar.txt"

While them in zsh:

    git add foo bar.txt
    git add 'foo bar.txt'
    git add "foo bar.txt"

The first one, where the pathname is not enclosed in quotes, should
escape the space with a backslash, just like bash completion does.
Otherwise, this leads git to think there are two files; foo, and
bar.txt.

The main cause of this behavior is __gitcomp_file_direct(). The both
implementions of bash and zsh are called with an argument 'foo bar.txt',
but only bash adds a backslash before a space on command line.

[1]: http://zsh.sourceforge.net/Doc/Release/Completion-Widgets.html

Signed-off-by: Chayoung You <yousbe@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

contrib/completion/git-completion.bash

@@ -2993,7 +2993,7 @@ if [[ -n ${ZSH_VERSION-} ]] &&
 
 		local IFS=$'\n'
 		compset -P '*[=:]'
-		compadd -Q -f -- ${=1} && _ret=0
+		compadd -f -- ${=1} && _ret=0
 	}
 
 	__gitcomp_file ()
@@ -3002,7 +3002,7 @@ if [[ -n ${ZSH_VERSION-} ]] &&
 
 		local IFS=$'\n'
 		compset -P '*[=:]'
-		compadd -Q -p "${2-}" -f -- ${=1} && _ret=0
+		compadd -p "${2-}" -f -- ${=1} && _ret=0
 	}
 
 	_git ()

contrib/completion/git-completion.zsh

@@ -99,7 +99,7 @@ __gitcomp_file_direct ()
 
 	local IFS=$'\n'
 	compset -P '*[=:]'
-	compadd -Q -f -- ${=1} && _ret=0
+	compadd -f -- ${=1} && _ret=0
 }
 
 __gitcomp_file ()
@@ -108,7 +108,7 @@ __gitcomp_file ()
 
 	local IFS=$'\n'
 	compset -P '*[=:]'
-	compadd -Q -p "${2-}" -f -- ${=1} && _ret=0
+	compadd -p "${2-}" -f -- ${=1} && _ret=0
 }
 
 __git_zsh_bash_func ()