extensions: recommend against using wrapfunction for repo methods
Instead, all extensions should use the "dynamic subclass" trick:
subclass repo.__class__ and then replace repo.__class__ with your new
subclass. This avoids conflicts that happen when one extension uses
wrapfunction and another uses subclassing to extend the same method of
localrepository.
os = <unloaded module 'os'>
os.system = <built-in function system>
os = <module 'os' from '?'>
util = <unloaded module 'util'>
util.system = <function system at 0x?>
util = <module 'mercurial.util' from '?'>
util.system = <function system at 0x?>
fred = <unloaded module 're'>
re = <unloaded module 'sys'>
fred = <unloaded module 're'>
fred.sub = <function sub at 0x?>
fred = <proxied module 're'>
re = <unloaded module 'sys'>
re.stderr = <open file '<stderr>', mode 'w' at 0x?>
re = <proxied module 'sys'>