Fix exception when making a directory that already exists

Summary:
There was a race condition where there could be an exception when trying to
create directories that already exist.

Test Plan: Ran the tests

Reviewers: #sourcecontrol, ttung

Differential Revision: https://phabricator.fb.com/D2736268

remotefilelog/fileserverclient.py

@@ -19,7 +19,11 @@ fetchmisses = 0
 _downloading = _('downloading')
 
 def makedirs(root, path, owner):
-    os.makedirs(path)
+    try:
+        os.makedirs(path)
+    except OSError, ex:
+        if ex.errno != errno.EEXIST:
+            raise
 
     while path != root:
         stat = os.stat(path)

remotefilelog/remotefilelog.py

@@ -6,7 +6,7 @@
 # GNU General Public License version 2 or any later version.
 
 import fileserverclient
-import collections, os, shutil
+import collections, errno, os, shutil
 from mercurial.node import bin, hex, nullid, nullrev
 from mercurial import revlog, mdiff, filelog, ancestor, error
 from mercurial.i18n import _
@@ -28,7 +28,11 @@ def _readfile(path):
 def _writefile(path, content):
     dirname = os.path.dirname(path)
     if not os.path.exists(dirname):
-        os.makedirs(dirname)
+        try:
+            os.makedirs(dirname)
+        except OSError, ex:
+            if ex.errno != errno.EEXIST:
+                raise
 
     f = open(path, "w")
     try:

remotefilelog/remotefilelogserver.py

@@ -12,7 +12,7 @@ from mercurial.hgweb import protocol as httpprotocol
 from mercurial.node import bin, hex, nullid, nullrev
 from mercurial.i18n import _
 import shallowrepo
-import stat, os, lz4, time
+import errno, stat, os, lz4, time
 
 try:
     from mercurial import streamclone
@@ -207,7 +207,12 @@ def _loadfileblob(repo, cachepath, path, node):
         try:
             dirname = os.path.dirname(filecachepath)
             if not os.path.exists(dirname):
-                os.makedirs(dirname)
+                try:
+                    os.makedirs(dirname)
+                except OSError, ex:
+                    if ex.errno != errno.EEXIST:
+                        raise
+
             f = None
             try:
                 f = util.atomictempfile(filecachepath, "w")