[PATCH v2] support for generating decreasing dates in bash 4.0 and 4.1

[Tomi Ollila <tomi.ollila@iki.fi>]

The printf builtin "%(fmt)T" specifier (which allows time values
to use strftime-like formatting) is introduced in bash 4.2.

Trying to execute this in pre-4.2 bash will fail -- and if this
happens execute the fallback piece of perl code to do the same thing.
---
 test/test-lib.sh | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/test/test-lib.sh b/test/test-lib.sh
index 78af170..a1c0f27 100644
--- a/test/test-lib.sh
+++ b/test/test-lib.sh
@@ -374,8 +374,12 @@ generate_message ()
 	# we use decreasing timestamps here for historical reasons;
 	# the existing test suite when we converted to unique timestamps just
 	# happened to have signicantly fewer failures with that choice.
-	template[date]=$(TZ=UTC printf "%(%a, %d %b %Y %T %z)T\n" \
-			$((978709437 - gen_msg_cnt)))
+	local date_secs=$((978709437 - gen_msg_cnt))
+	# printf %(..)T is bash 4.2+ feature. use perl fallback if needed...
+	TZ=UTC printf -v template[date] "%(%a, %d %b %Y %T %z)T" $date_secs 2>/dev/null ||
+	    template[date]=`perl -le 'use POSIX "strftime";
+				@time = gmtime '"$date_secs"';
+				print strftime "%a, %d %b %Y %T +0000", @time'`
     fi
 
     additional_headers=""
-- 
1.8.0