GPGDecrypt: Handle (un)encrypted files consistently

In the refactor to use the *Cmd events, an unencrypted file was simply
:read into the buffer.  This incorrectly caused an extra blank line to
be added to the top of the buffer.

The handling of encrypted files properly handles this, as well as
triggering BufRead(Pre,Post) events.

Instead of returning early for unencrypted files, go through the same
steps as for encrypted files (minus the encryption specific steps), thus
preserving the content of the original file.

plugin/gnupg.vim

@@ -562,44 +562,46 @@ function s:GPGDecrypt(bufread)
     echohl GPGWarning
     echom "File is not encrypted, all GPG functions disabled!"
     echohl None
-    exe printf('%sr %s', silent, fnameescape(filename))
-    call s:GPGDebug(3, "<<<<<<<< Leaving s:GPGDecrypt()")
-    return
   endif
 
+  let bufname = b:GPGEncrypted ? autocmd_filename : fnameescape(filename)
   if a:bufread
-    silent execute ':doautocmd BufReadPre ' . autocmd_filename
-    call s:GPGDebug(2, 'called BufReadPre autocommand for ' . autocmd_filename)
+    silent execute ':doautocmd BufReadPre ' . bufname
+    call s:GPGDebug(2, 'called BufReadPre autocommand for ' . bufname)
   else
-    silent execute ':doautocmd FileReadPre ' . autocmd_filename
-    call s:GPGDebug(2, 'called FileReadPre autocommand for ' . autocmd_filename)
+    silent execute ':doautocmd FileReadPre ' . bufname
+    call s:GPGDebug(2, 'called FileReadPre autocommand for ' . bufname)
   endif
 
-  " check if the message is armored
-  if (match(output, "gpg: armor header") >= 0)
-    call s:GPGDebug(1, "this file is armored")
-    let b:GPGOptions += ["armor"]
-  endif
-
-  " finally decrypt the buffer content
-  " since even with the --quiet option passphrase typos will be reported,
-  " we must redirect stderr (using shell temporarily)
-  call s:GPGDebug(1, "decrypting file")
-  let cmd = { 'level': 1, 'ex': silent . 'read ++edit !' }
-  let cmd.args = '--quiet --decrypt ' . s:shellescape(filename, 1)
-  call s:GPGExecute(cmd)
-
-  if (v:shell_error) " message could not be decrypted
-    echohl GPGError
-    let blackhole = input("Message could not be decrypted! (Press ENTER)")
-    echohl None
-    " Only wipeout the buffer if we were creating one to start with.
-    " FileReadCmd just reads the content into the existing buffer
-    if a:bufread
-      silent bwipeout!
+  if b:GPGEncrypted
+    " check if the message is armored
+    if (match(output, "gpg: armor header") >= 0)
+      call s:GPGDebug(1, "this file is armored")
+      let b:GPGOptions += ["armor"]
     endif
-    call s:GPGDebug(3, "<<<<<<<< Leaving s:GPGDecrypt()")
-    return
+
+    " finally decrypt the buffer content
+    " since even with the --quiet option passphrase typos will be reported,
+    " we must redirect stderr (using shell temporarily)
+    call s:GPGDebug(1, "decrypting file")
+    let cmd = { 'level': 1, 'ex': silent . 'read ++edit !' }
+    let cmd.args = '--quiet --decrypt ' . s:shellescape(filename, 1)
+    call s:GPGExecute(cmd)
+
+    if (v:shell_error) " message could not be decrypted
+      echohl GPGError
+      let blackhole = input("Message could not be decrypted! (Press ENTER)")
+      echohl None
+      " Only wipeout the buffer if we were creating one to start with.
+      " FileReadCmd just reads the content into the existing buffer
+      if a:bufread
+        silent bwipeout!
+      endif
+      call s:GPGDebug(3, "<<<<<<<< Leaving s:GPGDecrypt()")
+      return
+    endif
+  else
+    execute silent 'read' fnameescape(filename)
   endif
 
   if a:bufread
@@ -621,19 +623,21 @@ function s:GPGDecrypt(bufread)
     " - permissions don't allow writing
     let &readonly = &readonly || (filereadable(filename) && filewritable(filename) == 0)
     " call the autocommand for the file minus .gpg$
-    silent execute ':doautocmd BufReadPost ' . autocmd_filename
-    call s:GPGDebug(2, 'called BufReadPost autocommand for ' . autocmd_filename)
+    silent execute ':doautocmd BufReadPost ' . bufname
+    call s:GPGDebug(2, 'called BufReadPost autocommand for ' . bufname)
   else
     " call the autocommand for the file minus .gpg$
-    silent execute ':doautocmd FileReadPost ' . autocmd_filename
-    call s:GPGDebug(2, 'called FileReadPost autocommand for ' . autocmd_filename)
+    silent execute ':doautocmd FileReadPost ' . bufname
+    call s:GPGDebug(2, 'called FileReadPost autocommand for ' . bufname)
   endif
 
-  " Allow the user to define actions for GnuPG buffers
-  silent doautocmd User GnuPG
+  if b:GPGEncrypted
+    " Allow the user to define actions for GnuPG buffers
+    silent doautocmd User GnuPG
 
-  " refresh screen
-  redraw!
+    " refresh screen
+    redraw!
+  endif
 
   call s:GPGDebug(3, "<<<<<<<< Leaving s:GPGDecrypt()")
 endfunction