Repository: pandas-dev/pandas
Pull request: DOC: Add conda uninstall pandas to contributing guide
closes https://github.com/pandas-dev/pandas/issues/25487 
add command 
`conda uninstall --force pandas`

Problem statement:
DOC: Force Removal of pandas From Dependencies
From a discussion on Gitter with @TomAugspurger when following the pandas contributing guide the step:

```sh
conda env create -f environment.yml
```

Causes pandas to be installed in the environment from conda as a result of dependency resolution with third party libraries (ex: statsmodels, pyarrow, seaborn). 

To prevent undesired conflicts between the local development version and the installed version we should update the documentation to have an explicit removal of the bundled version as such:

```sh
conda uninstall --force pandas
```

Hints from issue discussion:
So you want to Update this section 
```
# Create and activate the build environment
conda env create -f environment.yml
conda activate pandas-dev
```

to be like that?

```
# Create and activate the build environment
conda uninstall --force pandas
conda env create -f environment.yml
conda activate pandas-dev
```

Swap the first and second lines but yes

Sent from my iPhone

> On Feb 28, 2019, at 2:45 PM, yehia67 <notifications@github.com> wrote:
> 
> So you want to Update this section
> 
> # Create and activate the build environment
> conda env create -f environment.yml
> conda activate pandas-dev
> to be like that?
> 
> # Create and activate the build environment
> conda uninstall --force pandas
> conda env create -f environment.yml
> conda activate pandas-dev
> —
> You are receiving this because you authored the thread.
> Reply to this email directly, view it on GitHub, or mute the thread.

okay

Commit message: Update contributing.rst

Patch to review:
diff --git a/doc/source/development/contributing.rst b/doc/source/development/contributing.rst
index 027f2d90bbb73..b893eb238eccb 100644
--- a/doc/source/development/contributing.rst
+++ b/doc/source/development/contributing.rst
@@ -177,6 +177,7 @@ We'll now kick off a three-step process:
 
    # Create and activate the build environment
    conda env create -f environment.yml
+   conda uninstall --force pandas
    conda activate pandas-dev
 
    # or with older versions of Anaconda:


Code review comments:
diff_hunk: @@ -177,6 +177,7 @@ We'll now kick off a three-step process:
 
    # Create and activate the build environment
    conda env create -f environment.yml
+   conda uninstall --force pandas
path: doc/source/development/contributing.rst
text: @user1:
You should activate before uninstalling. So swap this line and the next.