git-stash: add new 'pop' subcommand

This combines the existing stash subcommands 'apply' and 'drop' to
allow a single stash entry to be applied and then dropped, in other
words 'popped', from the stash list.

Signed-off-by: Brandon Casey <casey@nrlssc.navy.mil>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-stash.txt

@@ -8,7 +8,7 @@ git-stash - Stash the changes in a dirty working directory away
 SYNOPSIS
 --------
 [verse]
-'git-stash' (list | show [<stash>] | apply [<stash>] | clear | drop [<stash>])
+'git-stash' (list | show [<stash>] | apply [<stash>] | clear | drop [<stash>] | pop [<stash>])
 'git-stash' [save [<message>]]
 
 DESCRIPTION
@@ -90,6 +90,12 @@ drop [<stash>]::
 	Remove a single stashed state from the stash list. When no `<stash>`
 	is given, it removes the latest one. i.e. `stash@\{0}`
 
+pop [<stash>]::
+
+	Remove a single stashed state from the stash list and apply on top
+	of the current working tree state. When no `<stash>` is given,
+	`stash@\{0}` is assumed. See also `apply`.
+
 
 DISCUSSION
 ----------

git-stash.sh

@@ -1,7 +1,7 @@
 #!/bin/sh
 # Copyright (c) 2007, Nanako Shiraishi
 
-USAGE='[  | save | list | show | apply | clear | drop | create ]'
+USAGE='[  | save | list | show | apply | clear | drop | pop | create ]'
 
 SUBDIRECTORY_OK=Yes
 OPTIONS_SPEC=
@@ -256,6 +256,14 @@ drop)
 	shift
 	drop_stash "$@"
 	;;
+pop)
+	shift
+	if apply_stash "$@"
+	then
+		test -z "$unstash_index" || shift
+		drop_stash "$@"
+	fi
+	;;
 *)
 	if test $# -eq 0
 	then