tests: add missing interpreter lines

tests/test-hgweb-diffs

@@ -1,3 +1,5 b''
+#!/bin/sh
+
 echo % setting up repo
 hg init test
 cd test

tests/test-hgweb-filelog

@@ -1,3 +1,5 b''
+#!/bin/sh
+
 hg init test
 cd test
 

tests/test-hgweb-removed

@@ -1,3 +1,5 b''
+#!/bin/sh
+
 echo % setting up repo
 hg init test
 cd test

tests/test-issue1306

@@ -1,3 +1,5 b''
+#!/bin/sh
+
 echo % initialize remote repo with branches
 hg init remote
 cd remote

tests/test-issue842

@@ -1,3 +1,5 b''
+#!/bin/sh
+
 hg init test
 cd test
 echo foo > a

tests/test-mq-strip

@@ -1,3 +1,5 b''
+#!/bin/sh
+
 echo "[extensions]" >> $HGRCPATH
 echo "mq=" >> $HGRCPATH