scripts/bash_aliases: man_gitstaged(): Script around a porcelain git command

The output of 'git status' is not stable.

The more stable 'git status --porcelain' is more complex,
and scripting around it would be more complex.

However, 'git diff --staged --name-only' produces
the output that we were lookiong for.

Reported-by: Jakub Wilk <jwilk@jwilk.net>
Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>

scripts/bash_aliases

@@ -153,13 +153,11 @@ function pdfman()
 
 function man_gitstaged()
 {
-	git status							\
-	|sed "/Changes not staged for commit:/q"			\
-	|grep -E "^\s*(modified|deleted|new file):"			\
-	|sed "s/^.*:\s*/, /"						\
+	git diff --staged --name-only					\
+	|sed "s/$/, /"							\
 	|sed "s%man[1-9]/%%"						\
 	|tr -d '\n'							\
-	|sed "s/^, //"
+	|sed "s/, $//"
 }
 
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