ptx: avoid --format long option falling through into --help

* src/ptx.c (main): Add a 'break' after the --format handling case.
Otherwise it would fall through into the usage case.
* tests/misc/ptx.pl: Add test cases for --format=tex and --format=roff.
* NEWS (Bug fixes): Mention the fix.
Bug introduced in 1999-04-04 commit, SH-UTILS-1_16f-269-gd815c15.
Spotted by coverity (MISSING_BREAK).

1 files changed, 2 insertions, 0 deletions

diff --git a/src/ptx.c b/src/ptx.c
index 99da0cb5b..be342eefc 100644
--- a/src/ptx.c
+++ b/src/ptx.c
@@ -2015,6 +2015,8 @@ main (int argc, char **argv)
         case 10:
           output_format = XARGMATCH ("--format", optarg,
                                      format_args, format_vals);
+          break;
+
         case_GETOPT_HELP_CHAR;
 
         case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);