Michael Bolin <mbolin@fb.com> [Wed, 23 Aug 2017 18:24:57 +0000] rev 33999
dirstate: perform transactions with _copymap using single call, where possible
This replaces patterns such as this:
```
if f in self._copymap:
del self._copymap[f]
```
with this:
```
self._copymap.pop(f, None)
```
Although eliminating the extra lookup/call may be a negligible performance win
in the standard dirstate, alternative implementations, such as
[sqldirstate](https://bitbucket.org/facebook/hg-experimental/src/default/sqldirstate/)
may see a bigger win where each of these calls results in an RPC,
so the savings is greater.
Test Plan:
`make tests`
Differential Revision: https://phab.mercurial-scm.org/D493