In commit 936295c (Simplify commit and tag parsing, 2015-03-03), the
commit and tag parsing code was refactored. This broke tag messages in
ui-tag since the line after the tagger header was erroneously skipped.
Rework parse_user() and skip the line manually outside parse_user().

Signed-off-by: Lukas Fleischer <cgit@cryptocrack.de>

Fixes a regression introduced in commit 936295c (Simplify commit and tag
parsing, 2015-03-03).

Signed-off-by: Lukas Fleischer <cgit@cryptocrack.de>

If CGit is killed while it holds a lock on a cache slot (for example
because it is taking too long to generate a page), the lock file will be
left in place.  This prevents any future attempt to use the same slot
since it will fail to exclusively create the lock file.

Since CGit is the only program that should be manipulating lock files,
we can use advisory locking to detect whether another process is
actually using the lock file or if it is now stale.

I have confirmed that this works on Linux by setting a short TTL in a
custom cgitrc and running the following with CGit patched to print a
message to stderr if the fcntl(2) fails:

	$ export CGIT_CONFIG=$PWD/cgitrc
	$ export QUERY_STRING=url=cgit/tree/ui-shared.c
	$ ./cgit |
		grep -v -e '^<div class=.footer.>' \
			-e '^Last-Modified: ' \
			-e ^'Expires: ' >expect
	$ seq 50000 | dd bs=8192 |
		parallel -j200 "diff -u expect <(./cgit |
			grep -v -e '^<div class=.footer.>' \
				-e '^Last-Modified: ' \
				-e ^'Expires: ') || echo BAD"

This printed the fail message several times without ever printing "BAD".

Signed-off-by: John Keeping <john@keeping.me.uk>