Show presence of stashed changes in bash prompt.

Add a '$' in the __git_ps1 output to show stashed changes are present,
when GIT_PS1_SHOWSTASHSTATE is set to a nonempty value.

The code for checking if the stash has entries is taken from
'git-stash.sh'.

Signed-off-by: Daniel Trstenjak <daniel.trstenjak@online.de>
Acked-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

contrib/completion/git-completion.bash

@@ -40,6 +40,10 @@
 #       with the bash.showDirtyState variable, which defaults to true
 #       once GIT_PS1_SHOWDIRTYSTATE is enabled.
 #
+#       You can also see if currently something is stashed, by setting
+#       GIT_PS1_SHOWSTASHSTATE to a nonempty value. If something is stashed,
+#       then a '$' will be shown next to the branch name.
+#
 # To submit patches:
 #
 #    *) Read Documentation/SubmittingPatches
@@ -127,6 +131,7 @@ __git_ps1 ()
 
 		local w
 		local i
+		local s
 		local c
 
 		if [ "true" = "$(git rev-parse --is-inside-git-dir 2>/dev/null)" ]; then
@@ -148,12 +153,15 @@ __git_ps1 ()
 					fi
 				fi
 			fi
+			if [ -n "${GIT_PS1_SHOWSTASHSTATE-}" ]; then
+			        git rev-parse --verify refs/stash >/dev/null 2>&1 && s="$"
+			fi
 		fi
 
 		if [ -n "${1-}" ]; then
-			printf "$1" "$c${b##refs/heads/}$w$i$r"
+			printf "$1" "$c${b##refs/heads/}$w$i$s$r"
 		else
-			printf " (%s)" "$c${b##refs/heads/}$w$i$r"
+			printf " (%s)" "$c${b##refs/heads/}$w$i$s$r"
 		fi
 	fi
 }