Correct common spelling mistakes in comments and tests

Most of these were found using Lucas De Marchi's codespell tool.

Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Acked-by: Matthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/gitweb/gitweb.perl b/gitweb/gitweb.perl
index 1309196..80950c0 100755
--- a/gitweb/gitweb.perl
+++ b/gitweb/gitweb.perl
@@ -683,7 +683,7 @@
 	our $GITWEB_CONFIG_SYSTEM = $ENV{'GITWEB_CONFIG_SYSTEM'} || "++GITWEB_CONFIG_SYSTEM++";
 	our $GITWEB_CONFIG_COMMON = $ENV{'GITWEB_CONFIG_COMMON'} || "++GITWEB_CONFIG_COMMON++";
 
-	# Protect agains duplications of file names, to not read config twice.
+	# Protect against duplications of file names, to not read config twice.
 	# Only one of $GITWEB_CONFIG and $GITWEB_CONFIG_SYSTEM is used, so
 	# there possibility of duplication of filename there doesn't matter.
 	$GITWEB_CONFIG = ""        if ($GITWEB_CONFIG eq $GITWEB_CONFIG_COMMON);
@@ -1136,7 +1136,7 @@
 
 	# to avoid infinite loop where error occurs in die_error,
 	# change handler to default handler, disabling handle_errors_html
-	set_message("Error occured when inside die_error:\n$msg");
+	set_message("Error occurred when inside die_error:\n$msg");
 
 	# you cannot jump out of die_error when called as error handler;
 	# the subroutine set via CGI::Carp::set_message is called _after_
@@ -7485,7 +7485,7 @@
 		system(git_cmd(), "cat-file", '-e', $hash_base) == 0
 			or die_error(404, "Base object does not exist");
 
-		# here errors should not hapen
+		# here errors should not happen
 		open my $fd, "-|", git_cmd(), "ls-tree", $hash_base, "--", $file_name
 			or die_error(500, "Open git-ls-tree failed");
 		my $line = <$fd>;