advice: omit trailing whitespace

Git tools all consistently encourage users to avoid whitespaces at
the end of line by giving them features like "git diff --check" and
"git am --whitespace=fix".  Make sure that the advice messages we
give users avoid trailing whitespaces.  We shouldn't be wasting
vertical screen real estate by adding blank lines in advice messages
that are supposed to be concise hints, but as long as we write such
blank line in our "hints", we should do it right.

A test that expects the current behaviour of leaving trailing
whitespaces has been adjusted.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

advice.c

@@ -104,8 +104,9 @@ static void vadvise(const char *advice, int display_instructions,
 
 	for (cp = buf.buf; *cp; cp = np) {
 		np = strchrnul(cp, '\n');
-		fprintf(stderr,	_("%shint: %.*s%s\n"),
+		fprintf(stderr,	_("%shint:%s%.*s%s\n"),
 			advise_get_color(ADVICE_COLOR_HINT),
+			(np == cp) ? "" : " ",
 			(int)(np - cp), cp,
 			advise_get_color(ADVICE_COLOR_RESET));
 		if (*np)

t/t3200-branch.sh

@@ -1154,9 +1154,9 @@ test_expect_success 'avoid ambiguous track and advise' '
 	hint: tracking ref '\''refs/heads/main'\'':
 	hint:   ambi1
 	hint:   ambi2
-	hint: ''
+	hint:
 	hint: This is typically a configuration error.
-	hint: ''
+	hint:
 	hint: To support setting up tracking branches, ensure that
 	hint: different remotes'\'' fetch refspecs map into different
 	hint: tracking namespaces.

t/t7004-tag.sh

@@ -1777,10 +1777,10 @@ test_expect_success '--points-at finds annotated tags of tags' '
 '
 
 test_expect_success 'recursive tagging should give advice' '
-	sed -e "s/|$//" <<-EOF >expect &&
+	cat >expect <<-EOF &&
 	hint: You have created a nested tag. The object referred to by your new tag is
 	hint: already a tag. If you meant to tag the object that it points to, use:
-	hint: |
+	hint:
 	hint: 	git tag -f nested annotated-v4.0^{}
 	hint: Disable this message with "git config advice.nestedTag false"
 	EOF