grep: fix -o match with empty string (suggested by Colin Watson <cjwatson@ubuntu.com>)

function                                             old     new   delta
grep_file                                           1216    1251     +35

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/testsuite/grep.tests b/testsuite/grep.tests
index 520a1840f..ffce033e6 100755
--- a/testsuite/grep.tests
+++ b/testsuite/grep.tests
@@ -98,5 +98,9 @@ testing "grep -o does not loop forever" \
         'grep -o "[^/]*$"' \
         "test\n" \
         "" "/var/test\n"
+testing "grep -o does not loop forever on zero-length match" \
+        'grep -o "" | head -n1' \
+        "" \
+        "" "test\n"
 
 exit $FAILCOUNT