patch: Fix nullid for binary git diffs (issue4054)

The index for an empty file in git is not 0, but sha-1("blobl 0\0").

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branch : stable
hgweb: log headers only if headers were successfully parsed

The headers attribute is not initialized in certain error situations
(e.g. http 400 bad request). Check for self.headers before we attempt
to access it.

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branch : stable
extra : rebase_source : 91d35f625a0346ee28019d76b91903b314e73fce
test: make test-propertycache.py python2.4 compatible

The subprocess module have not `check_call` method in python2.4. Fall back to
calling `check` with return code verification.

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branch : stable
extra : rebase_source : ad59194855164e1799f4e5907433b2cf85f99bbe
hgweb: escape branch names in graph view

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branch : stable
extra : source : 75ce5ec573e5a07f91e9c0ec8fbd80a12438b42f
ui: send password prompts to stderr again (issue4056)

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branch : stable
extra : rebase_source : 1f571534d08389b9ac5550c464f75aa08e605d00
json: add more paranoid escaping

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branch : stable
extra : rebase_source : 726ecec2dfbd96d9a24767023ca283506d21104f
hgweb: add escaping of tags and bookmarks in graph view

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branch : stable