Remember non-yes answer for the current shell session

This basically caches $_autoenv_check_authorized_env_file in
$_autoenv_asked_already.  This should also improve the case for
authorized files.

Ref: https://github.com/Tarrasch/zsh-autoenv/issues/29

tests/autoenv.t

@@ -14,6 +14,7 @@ Now try to make it accept it
 
   $ _autoenv_stack_entered=()
   $ rm $AUTOENV_ENV_FILENAME
+  $ _autoenv_asked_already=()
   $ _autoenv_ask_for_yes() { echo "yes" }
   $ cd .
   Attempting to load unauthorized env file!
@@ -37,8 +38,9 @@ Now lets see that it actually checks the shasum value.
   $ cd .
   ENTERED
 
-  $ _autoenv_stack_entered=()
   $ rm $AUTOENV_ENV_FILENAME
+  $ _autoenv_stack_entered=()
+  $ _autoenv_asked_already=()
   $ test_autoenv_add_to_env $PWD/.env mischief
   $ cd .
   Attempting to load unauthorized env file!
@@ -56,8 +58,9 @@ Now lets see that it actually checks the shasum value.
 
 Now, will it take no for an answer?
 
-  $ _autoenv_stack_entered=()
   $ rm $AUTOENV_ENV_FILENAME
+  $ _autoenv_stack_entered=()
+  $ _autoenv_asked_already=()
   $ _autoenv_ask_for_yes() { echo "no"; return 1 }
   $ cd .
   Attempting to load unauthorized env file!
@@ -74,7 +77,8 @@ Now, will it take no for an answer?
 
 Lets also try one more time to ensure it didn't add it.
 
-  $ _autoenv_ask_for_yes() { echo "yes"; return 0 }
+  $ _autoenv_asked_already=()
+  $ _autoenv_ask_for_yes() { echo "no"; return 1 }
   $ cd .
   Attempting to load unauthorized env file!
   -* /tmp/cramtests-*/autoenv.t/.env (glob)
@@ -85,11 +89,35 @@ Lets also try one more time to ensure it didn't add it.
   
   **********************************************
   
+  Would you like to authorize it? (type 'yes') no
+
+And now see if we're not being asked again after not allowing it.
+
+  $ _autoenv_ask_for_yes() { echo "should_not_be_used"; return 1 }
+  $ cd .
+
+
+Reloading the script should keep the current state, e.g. when reloading your
+~/.zshrc.
+But it should re-ask for unauthorized files.
+
+  $ cd ..
+  $ $TEST_SOURCE_AUTOENV
+  $ _autoenv_ask_for_yes() { echo "yes"; return 0 }
+  $ cd -
+  Attempting to load unauthorized env file!
+  -* /tmp/cramtests-*/autoenv.t/.env (glob)
+  
+  **********************************************
+  
+  echo ENTERED
+  
+  **********************************************
+  
   Would you like to authorize it? (type 'yes') yes
   ENTERED
 
-Reloading the script should keep the current state, e.g. when reloading your
-~/.zshrc.
+With an authorized file, it should not re-ask you.
 
   $ $TEST_SOURCE_AUTOENV
   $ cd .

tests/leave.t

@@ -42,6 +42,7 @@ Leave the directory and answer "no".
 
   $ cd sub
   ENTERED
+  $ _autoenv_asked_already=()
   $ _autoenv_ask_for_yes() { echo "yes"; return 0 }
   $ cd ..
   Attempting to load unauthorized env file!

tests/recurse-upwards.t

@@ -110,6 +110,7 @@ Changing the root .env should trigger re-authentication via autoenv_source_paren
 First, let's answer "no".
 
   $ echo "echo NEW" >| .env
+  $ _autoenv_asked_already=()
   $ _autoenv_ask_for_yes() { echo "no"; return 1 }
   $ cd sub
   autoenv_source_parent_from_sub:
@@ -135,6 +136,7 @@ This currently does not trigger re-execution of the .env file.
 
 Touching the .env file will now source the parent env file.
 
+  $ _autoenv_asked_already=()
   $ touch -t 201401010104 .env
   $ cd .
   autoenv_source_parent_from_sub: