--- a/mercurial/posix.py Fri May 19 20:14:31 2017 -0700
+++ b/mercurial/posix.py Sun May 21 18:36:28 2017 -0400
@@ -244,7 +244,17 @@
# create a fixed file to link to; doesn't matter if it
# already exists.
target = 'checklink-target'
- open(os.path.join(cachedir, target), 'w').close()
+ try:
+ open(os.path.join(cachedir, target), 'w').close()
+ except IOError as inst:
+ if inst[0] == errno.EACCES:
+ # If we can't write to cachedir, just pretend
+ # that the fs is readonly and by association
+ # that the fs won't support symlinks. This
+ # seems like the least dangerous way to avoid
+ # data loss.
+ return False
+ raise
try:
os.symlink(target, name)
if cachedir is None: