gitweb: Make running t9501 test with '--debug' reliable and usable

Remove test_debug lines after 'snapshots: tgz only default format
enabled' and 'snapshots: all enabled in default, use default disabled
value' tests.  Those tests constitute of multiple gitweb_run
invocation, therefore outputting gitweb.output for the last gitweb_run
wouldn't help much in debugging test failure, and can only confuse.

For snapshot tests which check for "200 OK" status, change
  test_debug 'cat gitweb.output'
to
  test_debug 'cat gitweb.headers'
Otherwise when running this test with '--debug' option,
t/t9501-gitweb-standalone-http-status.sh would dump *binary data* (the
snapshot itself) to standard output, which can mess up state of terminal
due to term control characters which can be embedded in output.

Signed-off-by: Jakub Narebski <jnareb@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t9501-gitweb-standalone-http-status.sh

@@ -33,7 +33,6 @@ test_expect_success \
     grep "403 - Snapshot format not allowed" gitweb.output &&
     gitweb_run "p=.git;a=snapshot;h=HEAD;sf=zip" &&
     grep "403 - Unsupported snapshot format" gitweb.output'
-test_debug 'cat gitweb.output'
 
 
 cat >>gitweb_config.perl <<\EOF
@@ -50,7 +49,6 @@ test_expect_success \
     grep "403 - Snapshot format not allowed" gitweb.output &&
     gitweb_run "p=.git;a=snapshot;h=HEAD;sf=zip" &&
     grep "Status: 200 OK" gitweb.output'
-test_debug 'cat gitweb.output'
 
 
 cat >>gitweb_config.perl <<\EOF
@@ -72,7 +70,7 @@ test_expect_success \
     'snapshots: tgz explicitly enabled' \
     'gitweb_run "p=.git;a=snapshot;h=HEAD;sf=tgz" &&
     grep "Status: 200 OK" gitweb.output'
-test_debug 'cat gitweb.output'
+test_debug 'cat gitweb.headers'
 
 
 # ----------------------------------------------------------------------
@@ -82,7 +80,7 @@ test_expect_success 'snapshots: good tree-ish id' '
 	gitweb_run "p=.git;a=snapshot;h=master;sf=tgz" &&
 	grep "Status: 200 OK" gitweb.output
 '
-test_debug 'cat gitweb.output'
+test_debug 'cat gitweb.headers'
 
 test_expect_success 'snapshots: bad tree-ish id' '
 	gitweb_run "p=.git;a=snapshot;h=frizzumFrazzum;sf=tgz" &&
@@ -105,7 +103,7 @@ test_expect_success 'snapshots: good object id' '
 	gitweb_run "p=.git;a=snapshot;h=$ID;sf=tgz" &&
 	grep "Status: 200 OK" gitweb.output
 '
-test_debug 'cat gitweb.output'
+test_debug 'cat gitweb.headers'
 
 test_expect_success 'snapshots: bad object id' '
 	gitweb_run "p=.git;a=snapshot;h=abcdef01234;sf=tgz" &&