Disable the plugin when in a diff.

Closes #48.

Author: nathanaelkane

autoload/indent_guides.vim

@@ -33,7 +33,7 @@ endfunction
 function! indent_guides#enable()
   let g:indent_guides_autocmds_enabled = 1
 
-  if indent_guides#exclude_filetype()
+  if &diff || indent_guides#exclude_filetype()
     call indent_guides#clear_matches()
     return
   end

doc/indent_guides.txt

@@ -239,6 +239,7 @@ Bug reports, feedback, suggestions etc are welcomed.
   * Added way to override the default mapping (thanks xuhdev).
   * Added option g:|indent_guides_exclude_filetypes| to specify a list of
     filetypes to disable the plugin for.
+  * Disable the plugin when in a diff.
 
 1.6~
   * Added option g:|indent_guides_space_guides| to control whether spaces are