Issue generating a line plot from a Series when previous plots are already defined
#### Code Sample, a copy-pastable example if possible

```python
        df = self.getStats() # returns a dataFrame with a row called Rounds
        totalMatches = len(df)
        if (totalMatches == 0):
            print("Need to play at least one match for a graph", flush = True)
            return
        vc = df["Rounds"].value_counts()
        x = vc.plot(legend=True, figsize=[10, 8])
        x.set_xlabel("Number of Rounds to Win")
        x.set_ylabel("Occurrences")
        x.set_title("Value-Count Graph (Matches: " + str(totalMatches) + ")")
        
        Occurences = max(vc) + 1
        # for small values set y tic mark text
        if Occurences <= 20:
            yText = [] # Stores our Y-Axis text
            
            for i in range(1, Occurences):
                yText.append(f'${i}$')
            plt.yticks(np.arange(1, Occurences), yText, ha="center")
        
        plt.show()
```
#### The code above works fine unless the following has been executed to make "popout" graphs
%matplotlib qt5 

If a previous graph exists from a previous run, and is still up. Then this graph will have additions added directly to it. Please see the images for what is happening.

![Bug report for Pandas](https://user-images.githubusercontent.com/59935634/72558067-9b820d80-3867-11ea-9d69-cf424b63cc05.png)

It should be noted, I am using version 0.25.3 of pandas, and I searched and could not find this issue already logged.

1) The reason this is an issue is that it leads to potentially different results each time the program is executed. 
2) It only occurs with pandas Series objects. (I tested and it is not an issue for dataFrames.)

You can find the full python program at: 
https://github.com/RickOldenburger/War-Card-Game-Analysis

There is a work around and I have applied it in my program.
change the statement: 
x = vc.plot(legend=True, figsize=[10, 8])

to these two statments:
plt.figure(figsize=(10, 8))
x = vc.plot.line(legend=True) # no point in having the figsize defined twice


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#### Expected Output

#### Output of ``pd.show_versions()``

<details>

[paste the output of ``pd.show_versions()`` here below this line]

</details>
