git: check if gitignore already has file before modifying it

Signed-off-by: Ruslan Kuprieiev <[email protected]>

dvc/git_wrapper.py

@@ -96,6 +96,17 @@ class GitWrapperI(object):
     def commit_all_changes_and_log_status(self, message):
         pass
 
+    @staticmethod
+    def _file_contains(fname, s):
+        if not os.path.isfile(fname):
+            return False
+
+        with open(fname, 'r') as fd:
+            if s in fd.read():
+                return True
+
+        return False
+
     @staticmethod
     def modify_gitignore(flist):
         for fname in flist:
@@ -104,8 +115,13 @@ class GitWrapperI(object):
             # git and we will not have any problems with --porcelain output for
             # specific changed files.
             gitignore = os.path.join(os.path.dirname(fname), '.gitignore')
+            entry = os.path.basename(fname)
+
+            if GitWrapperI._file_contains(gitignore, entry + '\n'):
+                return
+
             with open(gitignore, 'a') as fd:
-                fd.write('\n' + os.path.basename(fname))
+                fd.write('\n' + entry)
 
 
 class GitWrapper(GitWrapperI):