py3: use pycompat.getcwd instead of os.getcwd

py3: use python 3 compatible variables in hgext/fsmontor/__init__.py Earlier this was left thinking that its part of pywatchman package. This patch replaces variables os.sep, sys.platform and os.envrion with their py3 compatible ones.

py3: add warnings in check-code related to py3 We have our own bytes versions of things like, getopt.getopt, os.sep, os.name, sys.executable, os.environ and few more for python 3 portability. Its better to come up with warnings if someone breaks the things which we have fixed. After this patch, check-code will warn us to use our bytes version. These checks run on mercurial/ and hgext/ and pycompat.py is excluded.

py3: replace os.getenv with pycompat.osgetenv os.getenv deals with unicodes on Python 3, so we have pycompat.osgetenv to deal with bytes. This patch replaces occurrences on os.getenv with pycompat.osgetenv

py3: have bytes version of os.getenv os.getenv() on python 3 deals with unicodes. If we want to pass bytes. we have os.getenvb() which deals with bytes. This patch adds up a pycompat.osgetenv which deals with bytes on both python 2 and 3.

url: remove unnecessary deletion of environ variables while dealing with proxy Currently we delete proxy environment variables if ui.config contains proxy values. This is unnecessary because urllib2.ProxyHandler class only reads proxy from environment it is initialised by None. But url.py never passes None, so there is no point urllib2 will take environment variables in account. This also prevents deleting environment variables which is not safe. This code was introduced while resolving Bug 2451 even it is in one of comments (sixth one) on bug that we can safely remove this part. Link to bug : https://bz.mercurial-scm.org/show_bug.cgi?id=2451

convert: add config option to control storing original revision common.commit.__init__ sets saverev=True by default. The side effect of this is that the hg sink will always set the "convert_revision" extras key to the commit being converted. This patch adds a config option to disable this behavior. While most consumers will want "convert_revision" to be a) written b) with the exact Git commit that was converted, some have use cases that prefer otherwise. In my case, I am performing significant rewrites of a Git repository *before* it is fed into `hg convert`. I have to do this because `hg convert` does not easily support the kind of transform I desire, even with extensions. (For the curious, I am "linearizing" the history of a GitHub repo by removing merge commits which add little value to the final history. It isn't easy to do this during `hg convert` because of Mercurial's file copy/rename metadata requirements.) In my scenario, my pre-convert transform stores a "convert_revision" key in the Git commit object containing the original Git commit ID. I want this original Git commit ID carried forward to Mercurial. By disabling the setting of this extra during `hg convert` and copying the value from the Git commit object, I can have the final "convert_revision" extra key contain the original Git commit ID. An added test verifies this exact scenario. This feature could likely be implemented for other VCS sources. But until someone needs the feature, I'm inclined to hold off implementing.

convert: add config option to copy extra keys from Git commits Git commit objects support storing arbitrary key-value metadata. While there is no user-facing mechanism in Git to record these values, some tools do record data here. Currently, `hg convert` only handles the "author," "committer," and "parent" keys in Git commit objects. All other keys are ignored. This means that any custom keys are lost when converting Git repos to Mercurial. This patch implements support for copying a whitelist of extra keys from Git commit objects to the "extras" dict of the destination. As the added tests demonstate, this allows extra metadata to be preserved during the conversion process. This patch stops short of converting all metadata to "extras." We could potentially implement this via `convert.git.extrakeys=*` or similar. But copying everything by default is a bit dangerous because if Git adds new keys to commit objects, we could find ourselves copying things that shouldn't be copied! This patch also assumes the source key is the same as the destination key. We could implement support for prefixing the output key to distinguish it as coming from Git. But until this feature is needed, I'm inclined to hold off implementing it.

convert: don't use {} as default argument value This is a common Python gotcha. I'm kinda surprised we don't have a check-code to detect this :/

documentation: better censor flag documentation